Both consoles have their pros and cons, I don't want to say one is better then the other, since it's a matter of opinion.
Having said that, in my opinion, PS3 takes the crown. But in this discussion, I'll be a neutral and list what's good and bad about both the 360 and the PS3.
360 - Pros.
- Cheaper console, cheaper games.
- Great online community
- Xbox Live have a lot of perks over PS Network.
- Halo, Gears of War, Fable, Mass Effect to name a few.
360 - Cons.
- Pay for Xbox Live subscription.
- Controllers aren't chargeable unless an extra battery pack is bought.
- Controllers aren't wireless unless a wireless pack is bought.
- (Personal Opinion) Xbox Live is filled (about 70%) with mouthy, crybaby, kids.
- Red. Ring. Of. Death. (Overheating)
PS3 - Pros.
- Free to join PSN and play online.
- USB charged controllers.
- Wireless controllers.
- Wireless bluetooth and headsets.
- (Personal Opinion) A maturer online community.
God of War, Gran Turismo, MGS, Uncharted, Killzone to name a few.
PS3 - Cons.
- Expensive console. Expensive games.
- Xbox Live has easier accessibility.
- Game Library isn't as big as the 360's.
Conclusion: I've owned both consoles. The main reason why I chose the PS3 over the 360 is because of the RROD. I owned the 360 first but twice it RROD'd on me. First time I had it fixed, second time I said fuck it and bought a PS3. In my personal opinion, I also prefer the stylish, modern look of the PS3 compared to the 360. But both consoles are great in their own ways. Another reason I chose PS3 is because it's RPG library. I'm an RPG fanatic and PS3 has the better upcoming choice of RPGs compared to the 360.
I played most of my COD4/World at War days on Xbox Live and nearly every other match, there was at least one or two whiny/mouthy kids spamming the mic. I grew tired but used to it before I owned a PS3. On the PSNetwork, this happens rarely. That's a huge plus for me.