I have a PS2 & a Cube. The only game on Xbox that interests me is Steel Batallion, and for my own good, I'm not going anywhere near it.
I think that I like the cube the best. I'm in love with Metal Gear & Viewtiful Joe. That being said, I'm a hardcore resident evil fan, and the cube sure has that one covered as well. Oh yeah, and there's Metroid & Zelda too. On top of that is the GB player for my GBA flash cart. I play my PS2 a lot too, and instead of an Xbox I have my Dreamcast which still kicks some serious ass.