I've burned out on WoW, had a couple of rebound resubs (usually around expansions or scrolls of resurrection and such) and never really got hooked by any other MMO after that. I've had a brief rommance with Cabal Online just because it felt fresh and different with its combo system - for what it's worth, it was fun while it lasted. Tried WAR too, was fun but quit after about 9 weeks.
Recently I've tried Tera (played for some 20 hours, didn't end up convinced) and The Secret World - a game with beautiful story, quests and mood, and a combat system devoid of all fun. Considdered resubbing past the first month but decided against it in the end.
Guild Wars 2 is fresh, fun, redefines a lot of stale MMO concepts, and the game gets more fun the more you play it. It starts off really fun but sort of uncomfortable, and from then it just grows on you bit by bit. Definitely the best MMO I've played since the amazing experience that was the vanilla WoW tried as a first MMO I've ever played, and leaves all the recent competition way behind. Give it a try.