360
I've owned both and just didn't like the PS3.
Feels cheap probably because the menu system is the same as my PSP 😕
Online stuff felt very clunky too.
The 360 has became a home media hub for me. Sky Player on it is fantastic, assuming you're already a sky subscriber. All the movies on demand, sports stuff on demand etc etc.
Stream all movies and music from my PC to the 360.
Last FM also available for free.
Zune for renting HD movies.
Online gaming "feels" a lot better on the 360. Yes you pay for it but you get your moneys worth. I still don't think the PS3 has a flagship game yet. GT5 has been delayed for far too long, Tomb Raider's too long in the tooth. Can't think of a stand out PS3 only game.
Lack of bluray may be an issue but word is a bluray player is coming for the 360 soon. Maybe internal, maybe external.