On 360:
The Gears of War series
Halo (never going to happen lol)
Braid. I really want to see what it's like.
Left 4 Dead. This may see a port, though. Valve don't seem to like exclusivity any more.
On Wii (but god, without the motion sensing)
Zelda: Twilight Princess
Brawl
But, there were far more games on the PS3 that I wanted, so that was my choice.