Warcraft is still my favorite. I thoroughly enjoy Guild Wars and The Old Republic, but WoW is the one I keep coming back to. Like Scottye Davis said, there is only so much content before you start to get bored. So usually I come back for a few months, have a lot of fun, then cancel my subscription for a while. It's a pretty good system because then I don't feel tied down by the game. It will be sad when the day comes that the WoW servers go quiet for good.