For me, both is the only answer,Which would you buy if you had neither at the moment?
if you didn't have either I would go with PS3 out of pure versitility, Bluray. media player. gaming and the online is free,
I'm a hardcore online gamer, mainly FPS, 360 is the only way to go,
IN MY OPINION Live blows the doors off the playstation network, especially when it comes to speed and reliability, there are a few features when it comes to partys that PS3 doesn't have as well,
I've always had party problems with PS3, I also find with fps's, xbox has a bit more competition when it comes to skill and ability, my KD's on PS3 are always a fair bit higher than on 360,
the $60 a year for Live wouldn't be worth it if you weren't right into gaming, and chances are if you don't have either yet, you aren't that into gaming