Ive got both ps3 and the xbox 360, and i can say the ps3 wins hands down, but there are some other things to consider in the argument, like price and reliability.
At first when the ps3 first came out i played on the xbox more because the games for the ps3 were not quite there, but now i play more on the ps3 and have given the xbox to my kids, as there are enough games to keep me occupied, COD4, GTA4, MGS4, FIFA etc...
The ps3 looks amazing and sleek, the xbox looks bulky and tacky compared to it
The ps3 online network is free and you have to pay for xbox live
But when it comes to reliability the xbox is KAK, sent mine back twice, but also my ps3 broke down recently and had to have a replacement, the cd drive went!!! so it might be that we are going to start seeing ps3 problems now they are getting to a year old.
Now consider the price you can get a xbox 360 for £149 now at
cheap xbox 360 and when you compare that to the £285 ps3 price tag then the xbox is serious value for money for someone who can't afford the ps3. So they both have advantages, and to summarise, if i was looking for a next gen console and had £300 to spend i would buy the PS3, and if i couldn't afford it i would buy the xbox!