Double Reversal
Both fights are all out.
1) Rots Dark side anakin vs ANH Ben kenobi (not counting the fact that in anh lucas didnt have computer graphics or advanced coreography)
<takes place on mustafar landing platform>
2) Anh vader vs rots obi wan on the death star. ( same deal with coreography n such)
1. Well, coreography aside, Old Ben was really a powerful Jedi. With the Force perhaps he would have a chance at defeating ROTS Anakin, but with a blade Anakin has this - he is better than Kenobi, and his endurance is much higher as he is in much better physical condition. Also on Mustafar he will be better able to do flips and stuff by the lava, Ben is far less agile.
2. May go either way. Vader could probably defeat him with the Force like Dooku did, however, Kenobi is better with a blade and is in better shape, more athletic and agile. If the fight leads to the lava river, Vader won't be leaping over the lava waterfall and onto a piece of flaoting junk like Anakin did, he'll probably fall into the lava and die. Overall? Depends on whether Vader uses the Force first or engages Kenobi in a saber duel, I'd say.