which class QQs the most (I know, I know, low blow-- but it made me laugh), but which class smiles the most? Skrattin (who is actually a Warlock himself) speculates that it's 'Locks who are happiest with the game. Even though they've taken some nerfs (although they might still be OP, depending on who you listen to), they still seem to be pretty happy with their class and the game at large. And it's true-- I've never once heard of a Warlock protest out there on the realms.
I generally think of Warriors are pretty happy guys, but even they have had their problems. And while most Priests I know tend to actually be pretty cheery about being the first to die when aggro is lost and playing whack-a-mole all the time, they've had their problems as well. And while I do like my Shaman, I can't really defend my class-- we're pretty big whiners (even if it is justified).
So maybe it's true-- Warlocks just might be the happiest class in the game. It's not that there isn't Warlock QQ, it's just that, for most of the game, it's been about 'locks, not by them.