UltimateUnknown on 20 July 2014
I have both and PS3 is by far the better option. Just has more variety and any type of game you may want to play.
Plus it has free MP as opposed to paid on 360 which may be a factor for you since you haven't got the successors and might be unwilling to pay to play online. If you do choose to go for one of the subscriptions, PS+ is once again the superior service.
