I say PS3 because of the cell, generally means equal graphics for both systems and bigger games, IMO. Not to mention that when the original is made on the 360 the PS3 port is usually inferior, whereas when its made for the PS3 the 360 port is generally identical(with the exception of FF XIII).
By bigger games I mean when PS3 developers make games they usually fill up the full 25gb on the Blu-Ray disc, which means that although the 360 port will have multiple discs, the game is generally bigger. Think about how much bigger the city in GTA IV could have been if it was developed for the PS3 and ported to the 360 with 2 discs.








