Right now, it'd be hard to not say the 360. Although I haven't tried either the Wii or PS3 (yet

) the 360 has amazing online in XBL, it has the best library of games by far (Gears of War, Oblivion, CoD3, CoD2, Ghost Recon: AW, and plenty to look forward to next year: Fable 2, Halo 3, Forza 2, Mass Effect). PS3 (at launch) has Resistance, which seems good although not spectacular, and CoD3... according to reviews, the PS3 version of CoD3 has framerate problems and reduced online functions. Besides that, PS3 has MGS4, which looks amazing, and a probable Killzone 2, which should be a hit if it is real.
The Wii has Legend of Zelda, but besides that, I don't see any MUST HAVES for the Wii yet. Red Steel looked like it would be good, but apparently it's a disaster.