Ps3 for sure. Free online play. With xbox you gotta pay like 7-8$ per month. But really you just need to figure out which games you wanna play cause each one has certain games that aren't on the other one
Whichever one your friends have, they are basically the exact same, graphics depend on the game for systems and even if there was a difference it would only be slight.
If you are planning on playing online get the 360 as the online is just overall better
but if you are poor and cant afford less than a dollar a day buy ps3