Well it depends what you're using the PC for because if you're using it just for gaming then I prefer a PS3 because it gives you more of that gaming feel, but if you're just using it as a normal PC then I prefer a PC because you can do so much more then on a PS3.
ps3 because you can go on the internet anyway... i think(i don't have one but my friend told me about it) and you can play awesome games like turok and heavanly sword with better graphics than the computer.