Probably Revan as the overall winner, as I think Vader would likely suffer a mortal injury in the battle.
That being said all 'game' heroes have an advantage over 'movie' hero's because game hero's are always OP.
Firstly Darth Vader was never strong enough to beat the Emperor in a fair fight, or he would have done it long before Luke came of age. Secondly Yoda was generally considered the strongest in the force on the Jedi side (movie era). On that basis I think the Emperor and Yoda go into the fight with a distinct advantage over Vader.
However Revan was created as the hero for KOTOR 1 & 2 and pretty much single handedly brought about the end of the Sith Empire. Much like Galen Marek (Starkiller - Force Unleashed) Revan was the typical 7 foot tall and bulletproof hero who could do things that no movie Sith or Jedi could. Its hard to compare apples with oranges. So if you did compare them all, the game hero has an unfair advantage. Thus Revan would beat everyone.
Preferably I think characters should be compared by genre, game hero to game hero and movie hero to movie hero. What about Revan v Starkiller? Seems to me Revan is the 'Ringer' in this scenario.
P.S. I was assuming you meant Emperor Palpatine and not the 'game' Emperor, who would beat everyone.