I'd say stick with PC because you can get the mods for stuff like better graphics, new quests, items, and weapons. You also get mouse and keyboard support for better in-game and menu control (not to mention UI mods). What's also helpful is that you can use console commands with the PC version which has actually helped me a few times to get through things faster (after I had already beaten the game once) and helped to unbreak a couple of quests.
I believe the PS3 version had a little big of a leg up on the 360 version with a little better loading times. However, there's also a large mandatory install on the PS3 version (around 4.5 gigs I believe).
You wont be able to escape an install either way so I'd say the PC version is the lesser of two evils :P
