I would get the ps3 version, but its up to you.
If you got a steering wheel for the 360 then get that one.
The 360 version runs considerably better. I was so disappointed with the ps3 version that I stopped playing it quickly, and will do so again on the pc after dealing with some technical issues.
PS3 versions of the CM F1 games always had frame rate issues so get the 360 version if you can. PC if possible at all.