Both the 360 and PS3 are great. Look at the exclusive titles for each, and decide which games look better to you.
I've owned both since launch, and I tell people that if you want single-player go PS3 because they have amazing exclusives; if you want multi-player and other online functionality, go 360.
Apologies, I meant PS4.... as of now with everything I am reading I am leaning towards the PS4 and selling off all things Microsoft.
My 360 is on it's last legs... if there is no release day backward compatibility then there is no use for my old games anyway.
I do not buy and keep a lot of games so I buy used games and as soon as I am done with them I put them up for sale. If I have to pay a fee to play a used game that is annoying. To me that is like if Marvel found a way to charge people for reading someone else's comic books.