Revan would probably win.
1. Force Lightning doesn't exactly play well with Vader's Suit.
2. Revan utilizes 2 sabers, while Vader has brute strength Revan has the speed advantage.
3. Revan took down the Star Forge defenses and then took down Bastila and Malek, I don't think Vader could have accomplished that.
4. Fact that Vader killed Younglings would probably annoy Revan, putting it mildly.
It would be a close match, but Revan probably has the advantage.
This is wrong on so many levels...