Nah if you own both console you can get ff13 in which platform you want it to.
If you only own a 360 of course you buy it for 360.
If you only own a ps3 of course you buy it for ps3.
The only difference that there is might be the multiple disk for 360 version but the game would still be running equally for both systems so saying 1 is gonna be better than the other like the OP and mr. 360 fanboy( you know who you are) is just plain BS.