Resistance 2, LittleBigPlanet, Valkyria Chronicles vs. Gears of War 2, Banjo-Kazooie: Nuts and Bolts, Fable 2 :

both have an adult shooter, a family friendly game, and a RPG exclusive to their console (tho there a differences btw the comparables, that's not what were looking at here) 

personally, i would go for Sony's line up (tho i have all of those games except Banjo Kazooie) 

obviously its not necessary, i was thinking the same, but GTA 4 was a bigger system seller for the 360 than the ps3, which surprised me

cause u'r almost certainly gonna have to pay extra, seeing as how they'll probably allow both silver and gold accounts to play

also, i only added ff Xi is the second comment cause i didn't want some suggesting that there was already an MMO on the 360... i just wanted to clarify that i wanted a GOOD (and realtime, for that matter) MMO for the consoles