It's really all a matter of opinion, because both systems have their pros and cons
Xbox Live seems like it has a faster, better connection, but you have to pay money for it.
Playstation Network is completely free, but sometimes unreliable.
The 360, from what I've seen and heard from other people, is not the sturdiest console ever built, and the interior is a bit of a mess. There's more chance (Again, just what I've heard. I've never owned a 360, but I've played games on them a lot) of games getting scratched or messed up. However, graphically, it's (in my opinion) just as good as the PS3, and the selection of games seems to be a bit nicer. It's also nice to have each individual player be able to sign into their own profiles, something Sony has yet to figure out... I don't really like the way that there are advertisements all over the interface of the Xbox, but that's just me
The PS3 is pretty sturdy. My little brothers throw it around like crazy, and it still runs like brand new. The interface is clean and organized, and nice and simple to use. It's graphically nice, about the same as the 360, but the selection of games isn't as great. They kind of missed out on Halo and a few other high-end franchises. You can only sign in to one profile at a time, and PSN tends to pitch a fit if you try to switch your account to a different profile on the same console. So, all guests that play with you get to start at the very beginning, no matter how many countless hours they've already put into a game on their own account. There was really only one thing that irked me about the PS3. It's not backwards compatible, unless you get one of the earliest versions of it. The big, fat ones with low memory. So, all of those PS2 games I had ready to play on the PS3 are kinda of just sitting there
My own humble opinion was just to go with the PS3, since I don't play any of the games that the PS3 doesn't offer. Free online gaming is quite nice, as well
That's about all I can think of, so I hope I helped