New concept, fun, keeps any friends you might have over happy, SSBB is the only game which could tear me away from my PC (SERIOUS PC bias here)
I tried an Xbox 360 at a friends house, it got the RROD while I was there, not too encouraging :/
PS3, never played and reviews conflict so much it's like one reviewer was reviewing an apple the other was reviewing an orange, but if it's as good as the PS2 it would be my no. 2 choice.