Okay, I am not a hard and fast supporter of either console, that said, I have a PS3 and the (old) xbox.
Now, It really just depends on what games you are wanting to play and how much you are willing to play.
If you want to play a lot of shooters, probably go 360, it has the big titles, Halo, GoW, etc.
If you want fighting/racing/adventure/RPG games, go PS3.
The PS3 has such stellar titles as Final Fantasy, Metal Gear Solid, Gran Turismo, Resistance, Ratchet and Clank, etc.
Also, the PS3's understated online component is very nice, and it is free, compared to the 360's LIVE service, which I believe to be $50/year.
Also, the PS3 is a BD player, and one of the very best...
But in the end, it is up to you, make your decision wisely, and don't listen to all the fanboys out there.