Played most (western) MMOs and while I'm not interested in the moment but in terms of game play I still reckon WoW has it down. Now, their community is total fucking filth and for that reason I would never recommend anyone play it but in terms of quest content, mechanics, polish they are leading the way.
Graphics are all a matter of personal choice of course. Personally, I loathe "realistic" graphics and find that WoW has a "house style" that is particular to Blizzard. If that's not your cup of tea, that's fine. I have a pretty middle of the range PC and it suits me as the more grunt the graphics engine needs, the more I am going to be pissed by choppy performance, FPS problems, anti-aliasing problems etc.
Graphics, particularly as a style, is a tricky point to argue IMHO.
Right now I am waiting to see what the Star Wars game is going to be like, I like their philosophy and they are grasping that releasing a half done game with a view to fixing it later is no longer acceptable to people. The content must be engaging and the mechanics must be polished and working. I have seen a fair few MMOs with potential fail by thinking that it is 2005 and they can release half a game.
