Xbox360 - Hands down.
Why?
360 has way more games out [and will get about everyone PS gets]
Elite has HDMI
Xbox Live is WAY more superior to PS online.
Achievements - HUGE reason if you like to get the most out of a game and not just beat it. it really brings out a lot more of the game, gives you more to do. - this is a huge one for me because if i can play it on ps3/xbox i always go xbox just for the achievments.
Elite 120 gig.
PS3 - has themes yeah thats cool i guess
free online play - cool better than paying 50 a year, but nowhere NEAR the quality as xboxlive
blu-ray high def movies. thats cool.
but yeah i say 360 hands down :) If i could go back i wouldnt even of bought my ps3 yet. i only bought it for bluray/final fantasy cuz its exclusive, but i got it when it was 600 brand new for 60 gig. BIG regret.