There is one thing you get with PS3 that you cannot get with Xbox or PC and that is you get the PS3 controller. Personally, I much prefer the PS3 controller to either an Xbox controller or the keyboard/mouse combo, which is why I play on a PS3.
One main reason I dislike the XBox very, very much is that clunky controller. And after playing MW a little on my PC, I realized that the PS3 controller is the best controller I have ever used in my whole life (Other than the N64 controller

). Mouse/Keyboard is really not all that bad and really intended for these games but since Skyrim was implemented with a console UI, I can't imagine it being very fluid and smooth on PC.
So yes, again I agree with one of Turja's many great points.