As much as I hate to say it for MMO, nothing will beat WoW, not until someone comes up with a radically different idea. I've played all the MMO's since 2004 and WoW keeps spankin them. Though I will throw in my hat and say if you like a game based heavily on lore and story and less on difficulty, LotRO is a great game.
As far as Non MMO? Hard to say...lots of great RPG's, FPS', etc. that have come out over the past year.