Irridium said:
PC.
Because of mods.
And if its laggy for you I suggest Oldblivion [http://www.oldblivion.com/], which lets the game run fairly well on old machines.
Seriously, mods are awesome.
Now that would have really helped before my cd broke (I was playing on my friend's house with my laptop). Now I either have to pirate it or buy a new one. *Sniff*. At least I have a map. It's like, synthetical and stuff, I think.
If I'd have (a working) Oblivion, then it would just be there. I'd play it (and I still try to) every once in a while to finally finish the campaign. It's just so long and the combat is frustrating.
Also, I started my first modding days there (which ended there, as well, since I didn't know how to do something in the tutorial).
EDIT:
Knusper said:
PC, but that's really because I have no need for any other platform. I would download a load of mods, but I don't really know where to get them
Try searching from http://www.tesnexus.com/ , or http://planetelderscrolls.gamespy.com/ .