I used to play WoW, and before that I played Everquest, which I thought was probably the best game I ever played. Not that I played that many but in EQ, I really liked the raids that had to be set up to go to the place where the biggest bosses were, (the name escapes me), and you had to have a good plan and good team to defeat them all.
I got pretty bored with WoW because it didn't have that teamwork kind of element that EQ did.