Honestly, once you take all the multiplatform games off that list (which are, except for Oblivion, better on the 360), you're left with some pretty slim pickins.
Resistance - IMHO, pretty crappy. It's just that since it was a launch game is got better reviews than it really deserved.
Ratchet - Good game, obviously, but it's really just an HD version of the previous games, minus online play.
Uncharted - Awesome. Probably best game on the system right now.
Heavenly Sword - Good, maybe even great, but waaaaaaaaaaay too short.
Warhawk - Probably the second best game on the PS3, but Live would have likely made this game even better.
Ninja Gaiden Sigma - It's just an upgraded version of Black. I'd definately buy it if it were $20 and I had a PS3, though, or if it came out on the 360. I'd rather have NG2, however.
Unreal Tournament 3 - A timed exclusive, I know, but the fact that user mods can actually be put in the game will likely solidify this as the best console version of the game. Live and the better-for-FPS 360 controller are obviously gonna sway some people to the 360 version, but the almost certain lack of user-created content will greatly trounce those issues.