360 Pros
Backwards Compatibility
Forza Motorsport 2
Halo 3
Lost Odyssey
Fable 2
Mass Effect*
Gears of War (1* & 2)
Ninja Gaiden II
Halo Wars
Left 4 Dead*
PS3 Pros
Blu-Ray
Killzone 2
Metal Gear Solid 4
Uncharted
Resistance (1 & 2)
Valkyria Chronicles
LittleBigPlanet
God of War 3
Gran Turismo 5
Free Wi-Fi
Free online
FFvXIII
360 Cons
Loud!
pay for online
PS3 Cons
Higher energy consumption
price
newer PS3s don't come with backwards compatibility
Debated
Quality of PS3 multiplats (Many say that the 360's look better/play better)
Ps3 has Mandatory Installs (I don't mind but some people do)
RRoD (Seems like an issue that has been dealt with, not sure though)
Personally I bought a 360 for GeOW, then it released on PC a year later. This angered me...I would rather play games on a PC than anything else. I barely use the 360. I suggest Ps3 (If you're willing to part with more $$).
*PC version also released