I've put a bit of time into all the available specs on live at 100, so I wrote out my thoughts on each one. Some thoughts include beta experience, too.
Priest
• Holy (3/4)
It feels a lot like it did in WoD, but the holy words make a big difference in spicing it up. The "holy form" talent cooldown is amazing, it basically lets you do your holy words like 4 times in 30 seconds. Feels like a 'playmaker' healer, especially in BGs because you pop your holy word on a guy and instantly the tides are turned. This is why I play healers in BGs, I want to ride up to a guy who's losing a 2v1, and blast a big heal on him, and frustrate the hell out of the guys he was fighting. And then the echo of light mastery keeps healing the guy for a HUGE hot and it just feels like what healing should feel like.
• Disc (2/4)
100% absolutely requires clique or mouseover macros, don't even think about using it otherwise. It seems incredible at 1v1 pvp. It's good enough for most mythic 5-man content and I think it might be really amazing for raid throughput healing. It's really hard to keep a bad tank alive, though. You can't really compensate for other people's errors with this spec as well as other healers can. Make sure you use power word shield a lot is all I can say. I think that people being bad at this spec is going to give it a bad reputation and it will be shunned from groups until blizzard over-buffs it to compensate. I would be worried about it having a bad reputation in the community.
• Shadow (2/4)
A cool spec, but I don't love it. It seems pretty good at pvp. It's a very 'plant your feet down' kind of spec, though, and doesn't stand up to melee pressure very well. This, along with Fury Warrior, has me scratching my head a bit about why everyone was gushing over it for so long in the alpha.
Mage
• Fire (3/4)
Very fun and smooth. It's more consistent and straightforward than Fire was in WoD, but that also means it's a lot simpler. For me, though, most of the fun was the way the old combustion worked, and that's just totally gone from the spec. I still like it, but I'm worried it might get boring. Still my favorite of the mage specs. I've been able to do the most dps on my fire mage of any of my characters that I've tried, and my fire mage is like 20 ilvls below my warrior.
• Frost (3/4)
Another fun spec. It's hard for me to say if I liked it better in WoD or not. I think WoD felt a little more fluid but this one has more options.
• Arcane (1/4)
Still doing the whole conserve phase/burn phase thing. It just doesn’t appeal to me. I tried all the talents but I didn't find anything exciting or interesting. Personal taste, but this is easily my least favorite casting spec. I don't care if it's super overpowered in the last tier like it was in WoD, I don't want to play this spec.
Warlock
• Demo (2/4)
After playing for a while I realized that if you cast Demonic Empowerment a lot more, the spec becomes way faster and better. With my talents you get a soul shard 50% of the time you empower demons and you get an instant cast demon bolt too. So I end up using it very often, after every hand of gul'dan and every dreadstalkers. Forget about the duration of the buff, just cast Demonic Empowerment every time you summon any demons. This helps you keep a ton of soul shards coming in. This spec is okay, but it doesn't seem to really 'shine' at anything. It's just a lot of casting and you do pretty good damage but it's not very satisfying.
• Destro (1/4)
Seems worse in every way than WoD, to me. Having to spec either shadowburn or chaos bolt...It just feels like less of a spec than it did in WoD. I know the the portals from the artifact are super important to the spec, so I'm sure it will be a lot better at 110. Right now, though, it's really bad.
• Afflic (3/4)
I need an add-on to help me manage soul effigy. Right now I just set it as my focus but I'd like a dedicated ui feature that makes it easy to see dots on it and target it quickly. Anyway, this spec is super strong and does a ton of damage and is amazing in pvp. I don't think I could play it as a main spec, though.
Note for all warlock specs: Thanks god mana tap doesn't seem to be the required 'best choice' talent so far. I hate that spell so much.
Rogue
• Sub (4/4)
Holy cow the animations look good. I love the new shadow dance. I love shadow strike. I love that they replaced slice and dice with symbols of death, which just costs a bit of energy and no combo points so you can use it before the pull without any fancy setup. Stealth having a 2 second cooldown combined with the teleport of shadow strike is just amazing for being out in the world questing. Stealth to an area with lots of mobs and shadow strike a couple times until the mob dies, immediately restealth and shadow strike to teleport to the next mob and kill it again…I have a talent that makes shadow strike stun mobs, too…It's just so good for that kind of situation.
• Assassination (2/4)
Feels a bit slow to me, after playing sub. I like exsanguinate (makes bleeds tick 400% faster) but I miss dispatch. I think this spec replaced WoD's sub as the 'complicated' rogue spec. It's definitely got a lot more going on than Assassination did in WoD. It seems strong, but I just like Sub so much more.
• Outlaw (3/4)
It's definitely more interesting than combat was in WoD. The new killing spree animation is great. The free pistol shots are a lot like dispatch was in WoD assassination and is a great way to add a bit of fun to the spec. I'm not sure what to do with Roll the Bones. Should I re-roll when I only get one buff? How many combo points should I spend per roll? I bet an add-on eventually will tell you exactly what to do and it will ruin the fun of it. Right now I'm just speccing Slice and Dice which I didn't expect I would do, but 90% haste from SnD is pretty amazing. Again, though, I'd rather play sub any day of the week.
Druid
• Feral (2/4)
Feels fine, a bit faster than in WoD. 10 second cooldown on stealth is painful after playing rogues with 2 second cooldowns. Rogue is just better to play, sorry cats.
• Balance (3/4)
This spec is great in pvp and it seems like it gets way better with the artifact. It's a lot of fun, but feels like it has a very long ramp-up time if you don't use the talents that give you instant cast star-whatevers and 60 lunar power on a short cooldown.
• Guardian (4/4)
Love it. My favorite tank spec. Animations and sound effects are fantastic. Ironfur is really cool. I love having a ton of HP. Has good self-healing but that isn't the focus of it's active mitiation. Great cooldowns. It's a really simple but still very engaging spec. I really like it.
• Resto (3/4)
Feels a lot like WoD but I appreciate some of the changes. I really like Flourish, the 100 talent that adds time to all of your HoTs duration. What can I say? It's resto druid. It's been very good for a long time and it still is. I found it really boring in Ashran and AV, unlike holy priest where I was having a ball, however. I think holy priest is just more fun, even if it turns out to be less powerful.
Monk
• Windwalker (4/4)
Another great melee spec. I love whirling dragon punch, it's amazing. Never pressing the same button twice in a row makes the spec really engaging, all the time. I think this is easily the best incarnation of WW in the history of monks. I mained WW in MoP.
• Mistweaver (3/4)
I love this one too. It's all about using Thunder Focus Tea to the utmost. I chose Focused Thunder for my 100 talent, which makes it a bit easier to manage. Throwing out 2 instant enveloping mists every 30 seconds is equal to a TON of priority healing. With mistwalk, tiger's lust, roll, and transfer, you become hilariously slippery in PVP. I can make rogues hate their lives with no effort when they try to keep up with me. The Chi-Ji cooldown is hilarious visually and actually really fun to use. It lasts 45 seconds on a 3 minute cooldown! I find it a bit harder to keep up with this spec in 5-mans, though, particularly timewalking. Tanks take a beating in timewalking and keeping tanks up without getting behind requires a whole lot more mental focus than the other healers (except disc). This was my favorite healing spec until I gave holy priest more chances.
• Brewmaster (2/4)
I wish I liked this spec more. I spend most of my time tanking mythic 5s and challenge modes so tank spec is really important to me. If I liked brewmaster more then Monk would be a no-brainer main class for me. It just feels like when things go wrong, they go REALLY wrong and you suddenly find yourself dead. Black Ox Brew goes a long way to covering your mistakes, though. I like the new expel harm a lot, but you only get one orb for every 100% of your hp that you lose, so you can't make much use of it in 5-mans. When taking big hits from raid bosses you always have 3-4 orbs around you and it's super strong, though.
I think my issue is that my instinct is to try to use Ironskin Brew and Purifying Brew to minimize the damage that goes through on parts that aren't actually that dangerous, and I end up not having enough charges for when things get rough. You basically always need to have 2-3 charges of your brews available in case the big damage starts coming in, so it's not a good idea to use your active mitigation at all unless you really need it at that time. So you end up just holding on to brews for most pulls and so you end up just only pushing damage buttons and it feels like playing an awful DPS spec. People make the same complaint about prot paladin but prot paladin at least pushes shield of the righteous to minimize damage on trash pulls. This spec you just feel like a shitty dps basically any time you're not tanking a big hard-hitting boss, which is when the spec gets a bit more fun.
According to blizzard this spec is meant to shine around the 35-60% hp range, which just doesn't appeal to me. I'd rather be a big bear with 10 million hp than a slippery monk with 5 million hp who is only good when he's below 3 million hp...
Another issue is that they completely screwed this spec out of its aoe-pulling abilities. Brew used to have the keg toss thing and could throw those around to pick up extra packs, but that's gone entirely. All that's left is keg smash (significant cooldown) and flame breath (significant cooldown). If you want to pick up 2 packs at the same time, you basically have to spec rushing jade wind, and even when you do you just feel like you're body pulling with RJW up. It feels awful. Please give the keg toss thing back, add a cooldown if you must (I think their artifact ability actually is basically this but I didn't try on beta).
Hunter
• Beast Mastery (3/4)
This spec is really simple, but I actually like it a lot. It's a cool looking spec and it feels pretty good to play. I love when your dire beast cooldown resets a few times in a row and you have a bunch of animals up all at once. It also makes your beastial wrath cooldown extremely short. Chimaera Shot makes the spec a lot faster, if you're someone who complains about downtime, but stomp is really satisfying to have available, too.
• Marksman (2/4)
I'm speccing sidewinders, which replaces both arcane shot and multi shot...The spec uses literally 3 buttons. It's not that bad, but it feels a little inconsistent. If you get a bunch of marked shot and lock and load procs you'll do insane damage. If you don't, you'll be casting a bunch of aimed shots and it's pretty boring. I'm not sure I could main this spec. Beast Mastery is more fun to me.
• Survival (2/4)
I think the grenades and caltrops theme is cool, but I'm not in love with the spec. It just didn't click with me in the short amount of time I gave it. I'll spend some more time on it later.
Shaman
• Resto (3/4)
People keep saying this is going to be the best healing spec but I'm not sure why. It feels a whole lot like it did in WoD. That's not a bad thing, but people weren't falling over themselves talking about how good resto shaman was in WoD, right? It did retain a lot of it's great cooldowns, and the artifact ability is really good. I like it, but I'm just not sure what all the fuss is about.
• Elemental (3/4)
Feels great, a satisfying, fast paced straightforward nuke caster. Big hits and lots of procs. I like it. If it wasn't for Fire and Frost Mage I would like this spec the most as a ranged dps.
• Enhancement (3/4)
Another great melee. The rotation is a bit simple, but you can make it more complicated with talents. It feels great, and man does the artifact ability feel good to use. Great animations. Super squishy in PVP, but you also just rip people apart at 110 so it's a two-way street. Every time I try Fury warrior I just think "Enhancement is so much more fun than this…"
Warrior
• Fury (2/4)
So disappointed. The animations are great, yeah. And it's better than the shitshow of WoD fury's RNG nightmare. But it hasn't been fun for me. I'm still giving it more and more time because I really wanted this spec to be the one for me, but I haven't enjoyed it so far. Enhancement just blows it out of the park, in my opinion. I'm still trying to figure out why people keep gushing about this spec. The animations are great, sure, but the gameplay hasn't clicked for me.
• Arms (3/4)
Way better than in WoD, but that doesn't say much. Sometimes colossal smash resets like 5 times in a row and it feels awesome. Overpower makes the spec feel way more interesting to play. The execute phase rotation seems super boring, though, which is surprising. Who would have thought that execute phases would be unfun for an arms warrior?
• Protection (3/4)
Ignore pain is MASSIVE. It's extremely good. In timewalking dungeons, I can easily solo pulls as long as I keep ignore pain up. The instant that ignore pain falls off, I go to half health and feel like I'm going to die. This is made worse by the fact that healers just start ignoring you if you keep ignore pain on 90% of the time, because you don't need healing as long as you have IP. Then suddenly you lose IP and don't have rage and your healer isn't paying attention to you and it gets dangerous.
I don't have any faith that they're going to do rage generation right for this spec.
Death Knight
• Frost (3/4)
I like this spec. It fixes the problems it had in WoD, but it's still basically the same thing. It's very enjoyable, but I'd pick enhancement over it for a dual-wield dps. The abilities look really great and the class 'fantasy' is totally on-point.
• Unholy (3/4)
I love what they've done with unholy, and it's even better with the artifact ability. AOE is really simple to set up and so strong. My favorite 2h dps spec.
• Blood (3/4)
Still great. I've always loved blood tanking, and I still love this one. I think it was as good or possibly better in WoD, though. Still a great spec. I give Guardian the edge over blood because it feels more consistent, where blood sometimes feels rune-capped and can get a little clunky at times. My Blood DK is much stronger gear-wise than my druid, but I'd still rather take my druid to most instances.
Paladin
• Holy (2/4)
I like it for the most part. The mastery is stupid, but you can spec into beacon of the lightbringer to basically just ignore it. I actually thought holy power worked really well for holy paladin in WoD, so losing it is kind of strange. It's still a great healing spec, though. Has a crazy number of very good cooldowns. Devotion aura with aura mastery is insane and I feel like raid leaders will design raid strategies around it. Without any absorbs this spec feels a lot like it did in WotLK to me. The artifact ability is really cool, but it's a bit fire-and-forget.
• Retribution (2/4)
The spec is decent but it's the only melee spec that feels like it has a set 'rotation' anymore. I feel like I'm just doing the exact same loop that lasts 2 judgements over and over. There's nothing hard about setting up the judgement windows, it just feels a bit 'fixed', like you would handle every pull exactly the same. I think I'd get tired of this spec pretty quickly.
• Protection (2/4)
Yeah, it only has one thing to think about as far as mitigation goes, and that's dumb, but damned if it isn't very effective. I love Blessed Hammers, so cool. I am surprised at how shitty the self-heal is. I though that thing would be great, but in practice it's basically the worst tank for self-healing in the game (provided you consider ignore pain to be 'healing').
