I am probably one of the only people to choose 360 over PC. I like the 360 much better because I despise using a keyboard and mouse, it feels so alien to me, especially since I grew up playing games on the Nintendo 64 like Zelda and James Bond.
Another reason is I waste all my time modding the game instead of enjoying it, it's like an addiction... to go out and find every mod that sounds remotely interesting and then adding it to the game then loading up a character just to see what it's like. Along with that I've had to reinstall Oblivion too many times because the mods !@#$%^ it up. I have considered limiting myself to a certain number of mods and using my Xbox controller instead of the keyboard and mouse, but all I have are wireless controllers and no money to go get a wired controller or adapter.
There is also the comfort aspect, it is much more enjoyable to relax in your favorite chair or lounge in bed and play Oblivion and enjoy all it has to offer.
So obviously
my choice is the Xbox 360 version