we have a 360 and a WII and the 360 is miles ahead in graphics and stuff but for full body involvement you just cant beat the WII
if you like the motion control, check out project natal (think that is how it is spelt - don't have my xbox mag at the moment) for the 360 - motion control without the need for a controller.
for me i love the old xbox, chipped so i can play the arcade emulators - go bubblebobble