If by some miraculous means I get a Xbox 360, I would get Dead Rising, Oblivion, Fable 2 (when it comes out), Tony Hawks Project 8, Viva Pinata... there was more but I have seem to have forgotton titles.
The main reason I would choose 360 of Wii and PS3 is because 360 has been out for a year now and most (if not all) of the bugs and glitches have been fixed. They have a solid foundation of games and most of them are solid titles. The Wii and PS3 are still full of bugs and glitches (according to my knowledge, someone please challenge that) and not a lot of good launch titles, although the Wii had LoZ: Twilight Princess so I don't know. The Wii's strap breaks so I am going to wait untill thats fixed and the PS3's is insane so I am going to wait for a price drop.
Thats that for that rant. Feel free to criticize my inferior intellect and to make corrections. kthxbye