WoW is in it's slow decline. You can feel it when you log in. Everything is being rehashed, it's getting repetitive and tedious (even for an MMO!), and everything just feels like it's been done before. I log in every few days and just ask myself... why am I still playing this game? It's really depressing because I want so badly for it to be fun again, like it was in vanilla, BC, and the last few months of WotLK. It just isn't though. I'm not sure if it's the fault of the designers getting complacent, or if I've just grown tired of the game in general. I do however, know that I am not alone in these feelings regarding WoW. Many of my friends feel the same way.
So my next MMO will be SWTOR. The story elements sound awesome, the raids with individual loot containers sound awesome, and the classes all seem fairly unique and interesting. We'll see if it lives up to the hype, but so far it looks great.