I'd love a multiplayer, cell shaded, comix-zone game. I think with any of the 3 new systems power it would look amazing. Plus beat 'em up games seriously need some invigoration this gen.
Bushido Blade for the wii (Listen to me SE!!) Even i would like gesture based realistic samurai fighting.
Umihara Kawase for the wii ala bionic commando but bright and pretty.
Mega Man Legends nuff said
any good x-men game that can capture the fun spirit of the old 16 bit ones.