You can't go wrong with WoW. It can cater to almost every type of MMO player- casual, role-players, PvP junkies, ect. I think it lacks depth in many areas, but it has so much polish in what it does have.

Personally, after a year away, I got lured into Vanguard again when they offered me another free trial. PvP is virtually non-existent, but that never bothered me. Also, after all that time it still feels unfinished in some ways. But what I always liked about the game is it's complex (compared to WoW) crafting and diplomacy systems and it's expansive open world- if you can see it, you can go to it. I don't know if I'll stick with it this time either, but I really do appreciate the game for the potential it offers.