The Shaman meta is so awful right now. There's no stand-out deck that I can see. Pre-Naxx, Shaman was successful on the back of highly efficient spells, namely, Hex, Lightning Storm, and Lightning Bolt. Backing that up with some Windfury/Rockbiter shenanigans (be it in the form of Al'akir or pre-nerf Leeroy) and you could develop a competent threat. I'd say Crusher Shaman was the most well-known of pre-Naxx Shaman decks, and it was pretty fun to play.
Then Naxxramas dropped, and I feel like aggro decks were significantly buffed. Nerubian Egg, Undertaker, and Haunted Creeper being the major buffs, allowing Zoo and Aggro Hunter to strengthen and as a consequence the relatively slow Shaman decks, lacking any form of healing or efficient card draw, started to weaken. They didn't entirely fall out of favor, but simply were weaker.
Now, in a GvG meta, Shaman really has been hit badly. It isn't so much that Shaman became inherently weaker, but rather, they received so few good class cards compared to other classes that they simply have fallen behind. I mean, look at the list of cards:
Ancestor's Call: Too RNG-based to be worthwhile
Powermace: Average, great in Arena, so far no one has made a great ShaMech deck though
Whirling Zap-o-Matic: Average, but dies too easily. Great in Arena.
Crackle: Good-to-great... one of the only playable Shaman GvG cards.
Vitality Totem: Just doesn't do enough even if it hypothetically shores up one of the weaknesses of Shaman (lack of healing)
Siltfin Spiritwalker: Only playable in Shamurloc decks... which don't work so well, sadly
Dunemaul Shaman: Just bad, straight bad
Neptulon: Actually a decent Legendary... The major problem is that he is so weak to BGH, but just like Dr. Boom, he can overcome that weakness by requiring your opponent to still deal with 4 more cards
So, when I see that list, I see really only 2 or 3 cards worth playing: Crackle for sure, Neptulon possibly, and maybe-just-maybe Powermace if you are trying a ShaMech deck. Every other card is too niche or just outright bad to be used with any consistency.
The thing is, Shaman is my favorite class. It was the first real class I tried to play or deck-build with and is my most-played class to this day, Priest being my secondary. With that said, I've got about 4 Shaman decks I'm playing around with right now, but so far, the most successful one I've found is my Soka Shaman deck:
I don't know how you'd classify this deck and I'm still working on moving things around, but, it has worked pretty well for me so far this season. There are probably two major areas that I'm considering re-working: 1) limited card-draw as all I have is Mana Tide Totem and Bloodmage Thalnos and 2) Feugan, Stalagg, and Baron Rivendare being a bit abnormal.
The card draw hasn't actually been as big of a problem as you might expect. I have enough silence targets in the deck that if they blow a silence on Mana Tide then I usually can make them pay for it later with some other minion... and of course the dream of Mana Tide popping up behind Feral Spirit is pretty much an insta-win if they don't stop it within a turn or so. The major reason card draw isn't a huge issue is because I'm running so many high-value minions. Sylvanas, Dr. Boom, and Neptulon each trade often 2-1, but can get even higher value depending on the board situation, especially if I throw down a Baron Rivendare with Sylvanas or the Boom Bots.
As for Feugan, Stalagg, and Baron... this deck used to be my Shaman Deathrattle deck with some Reincarnate action, but I've since re-arranged it a bit. Now, Stalagg and Feugan still serve as an extra means to buff an Undertaker if I draw it late in the game, but I also find they are decent minions as-is. Baron works with almost 1/3rd of the cards in the deck, so I find he has a decent place. If I drop off the Feugan/Stalagg twins I may consider removing Baron too, but for now, I enjoy having them all there and I'm not sure what I'd replace them for anyway.
Finally, Antique Healbot is the all-time MVP against aggro decks. I found that in the Naxx meta, Shaman would often stabilize against aggro around turn 6-8... but by then, it was too late, and they could burn down your last few HP with Soulfire, Hunter hero power, etc. Now though, if I can pull out that single Healbot, it gives me enough to get back into many matches that would have been long lost without it.
So, I'm enjoying it so far and find it wins more than it loses but there are probably still kinks to iron out. If anyone has any comments I'd be happy to hear them.