It's actually insane how limited classes are after so many expansions. I'd only call Mage a complete class, sure most people just faceroll with Tempo Mage but that's what the ladder system rewards, you can really do a lot with that class and have decent success.
You can make a case for Warlock being there as well, it's definitely close since Reno was printed. They are going to lose Demons unfortunately but they've got such a wide range of tools and the best hero power that it takes probably the least amount of new cards out of all classes to establish a new archetype.
Paladin is the most binary shit, board board board face face face with the occasional value trade no matter which version you play (except for Anyfin which is getting gutted).
Shaman lmao, only became playable once it got Trogglord and enough burn to raze a city. Only a single viable list.
Rogue is eh, only the combo lists are competitive and those are all rather similar in playstyle. There are tons of different Rogue lists but they're all low tier and full of unfinished ideas.
Warrior at least retained an alternative to the eternal Control archetype, albeit an arguably much less exciting one since the execution of Warsong. Anything else they tried with the class fell flat on its face.
Druid, one word: BrokeBack
Priest is fair, they got decent variety and Blitz did a good job with Dragon Priest, the only issue is that all lists are just that: fair. And fair just doesn't cut it in Hearthstone. It's okay though.
And Hunter will continue to be Hunter for a long, long time.