A system is only as good as the games it has. Your choice should be what games do you like not so much the console.
Outside of the Gears of War 1 (didn't like 2) And forza. I could give a damn about my 360.
I did get Call of Duty for the 360 for *live* however I know tons of people who play it on the PS3 and never bitch about it.
Fall out 3 rocks, bought it for PS3
Oblivion rocks, bought it for Ps3
Street Fighter 4 kicks ass, bought it for PS3 *would rather of had it for 360 due to xboxlive, however xbox + dpad = TOTAL FIAL!
I bought Halo 3 for 360 and sold it a week or two later.
There's sooooo many kick ass games for the 360 VS the PS3!!!!! however when it comes down to it I really can't think of all that many. Most of the good games are on both systems.
The argument was much more true when the PS3 first came out, but it was a stupid one at that, 360 out for 1+ year, xbox 360 didn't get any really good games til 1 year in when Gears of War came out, just look at NPD charts and you'll see how the 360 system sales took off like a bat outta hell with Gears.
As of right now, there really isn't a lack of games for either system.
I've said it before and I'll say it again.
If I only played online with friends with out a doubt I'd buy a 360 or even 2 just to have an extra one for a backup.
If playing online was a 2nd thought then with out a doubt I would buy a PS3 over the 360. I like the system better, I like the menus, I like the controllers, I love how the PSN gives you real prices and not BS credits that always leave you with random left over credits that are just under what you need so you have to buy more to get something else to use them up.... I also love how the controllers on the PS3 stay charged for a long time. My 360 controllers eat batteries faster then Bs dildos.
What it comes down to is fan boys. The 360 will always be better because of the fan boys. Even if the PS3 were to have more games, more units sold, cheaper prices, and free add ons, guess what? the 360 would still be better.
Just look at Halo 3, no matter how shitty that game is, it will always be the BEST fps to the 360 fan boys. Call of Duty while clearly a better game, no matter what, will never be better then halo.