It's simple.
Content: PS3 version.
Stability: 360 version.
Of the little time I was able to play online with the PS3 version, the online servers seemed a lot slower. The menus and title screen also took a lot longer to load. This, combined with the slow-down during gameplay, makes the 360 version superior in terms of performance. That being said, the PS3 version gets an exclusive character, and I happen to think that the PS3 controller is a little more suited to the game. It's really personal preference.
Content: PS3 version.
Stability: 360 version.
Of the little time I was able to play online with the PS3 version, the online servers seemed a lot slower. The menus and title screen also took a lot longer to load. This, combined with the slow-down during gameplay, makes the 360 version superior in terms of performance. That being said, the PS3 version gets an exclusive character, and I happen to think that the PS3 controller is a little more suited to the game. It's really personal preference.