I'd get a PS3. Imo, it's got some better series and exclusive devs, it also has free online and has built in wifi.
The 360's got Rare and uh... no other company comes to mine when thinking of first party games. Not to mention, it'll most likely break on you, you have to pay money to use it online, and wifi adapters are $100.
PS3s also have Bluray, which I actually think is awesome, I've bought a bunch of Bluray movies and enjoy watching them on my PS3.