I would definitely say warlocks. The warlock as a class got revamped in MoP so hard and it has become such a complex class in terms of everything. Just think of the viable talent choices (pet vs no pet), all the different resource types they have on different specs (soul shard, demonic fury, burning ember), not to mention that all the 3 specs are fairly viable (as far as I know demonology is nearly as good as affliction in high-end gear, not to mention that destruction is already a must for some fights). Playing skillfully, seizing the opportunities, feeling the class, and using all that the class got is far more rewarding of when it comes to fun (enjoying the character you are playing with) and to performance (warlock dps is quite nice if played properly) in this expansion. I would say that this is how a class should look like in 2013 and not as retarded as mage, for example. I've been playing with mage since the beginning of Wow, and I do feel that mage as a class is nowhere near in terms of complexity or possibilities as locks. The state of the mage class feels pretty much the same as it was 2 expansions before, there's basically nothing new to it. Mages would desperately need a pet (on all specs) to make things a bit more interesting, or at least a resource system which would bring the need for some brain to the class instead of hoping for crits. The only talent that makes mage specs somewhat different to play (apart from the lvl 90 talents among which Invocation is the only viable for pve) is the Bomb tier. I am fairly disappointed because if blizzard could revamp locks this good, why didn't they try to export just a fragment of locks' complexity, variety and awesomeness to the mage class?