i do have both consoles (actually every major recent platform outside of the DSI and PSPGO)
I enjoyed my 360 and enjoy my PS3. the PS3 gets more use due to the fact that it has a a blu ray player, and its a wee bit better on the media streaming support (though i havent tried on the 360 in a while).
I would recommend compiling a list of the exclusives that you want and see which platform has more of the ones you want to play. Get that one.
or you could always do what i did, get one and in about 5 or 6 months get the other. That way you can have the best of both worlds