Well i have had both, but i got rid of my xbox for the ps3 (due to the blu-ray player) but people will most probaly say xbox due to ps3 getting hacked and being down for a month (playsation store still down) and with multyplayer coming back online they made a bigg security flaw when going back online with changing your ps3 password lol
also when i had the xbox if i nocked or moved the xbox while a game was inside it would burn threw that disc so i would have to go the local game shop to get the disc layer fixed, saying that there has been many manafacturing fault's with the 360 but they could have been fixed up by now.
So i would say ps3 since playing online is free ;p