But yeah anyway...
Price - Cheaper to buy 360, but perhaps in the long run (depending on when a new console comes out)...online fees of the 360 will probably make the difference minimal.
Games - Depends on what you like. Both have quite a lot of exclusives...you might want the PS3 ones or the 360 ones more. One thing you might want to consider is that a few 360 games not on the PS3 could be bought on the PC.
http://en.wikipedia.org/wiki/Category:PlayStation_3-only_games
http://en.wikipedia.org/wiki/Category:Xbox_360-only_games
Have a look through those to see what you might be missing out on. Dunno if it includes all up-and-coming games though.
Quality - Debatable. In the end it's not that different.
Extras - PS3 has a blu-ray player if that is something you want....and Home which is quite a nice free application with some fun arcade games...looks a bit like Second Life. Don't even know what the 360 has extra to the PS3. Some avatar stuff??? From what I know....nothing I would care about having.
Online - Some say that 360 online is better...but is it worth the cost? Up to you, but most of the time I can play games and have no issues...some untrue stereotypes come into place when you talk about 10 year olds being on PS3 and there being friendly people on 360.....It depends on what you want really, but if you just want to play online games then either are good. If PS3 ever gets in-game private mic chat rooms (only got text chat ones atm) then there'd be no difference in my online experience at all.
Friends - Only something you can answer.......if playing with your friends is something you do a lot then get the console they have.