Whichever version you pick it up for AVOID MODS.
Really?
MODs are what you use to inject life into something you've played to death and they change the game into something different than it already is.
They are also what you use to fix the glaringly obvious issues in Oblivion
The game works great and all the issues patched via XBox LIVE.
Really? all 1000+ bugs that the unofficial Oblivion patch fixes are available for Xbox 360?
If you have it for the 360 you know it will look great and play great and have no serious glitches.
how about getting stuck in a rock or tree?
A few months ago i would have agreed that the Xbox 360 version is perfect and i would still happily play where no other option available but i can't now for the life of me see why anybody would suggest a broken buggy console version over a modded PC version with 1000+ bug fixes and no broken level/creature scaling issues.
Please note i am not flaming consoles here, i see the attraction of relaxing on the couch with a control pad and have done so for many years but telling somebody to play a glitchy/buggy game when they have the pc version available to them is IMO bad advice.