If you like multiplayer: Xbox 360
If you like single player: PS3
If you like less complicated and just plain fun, albeit not very visually pleasing: Wii
I wish there was one that had a built in Blu-ray player like the PS3, a multiplaer support system like Xbox Live, and the accessibility of the Wii. That would be a truly great system. I personally went with the 360 because it has a bit of everything and rules online gaming for the moment, which is what I play a lot.