Well, I read what Darth Vader (EU) feats were in a mini respect thread, and, it doesn't even come close to what a Heaven Ascension Dio can do, if Vader confronts this Dio, then the latter stomps, and hard, like, really hard.
Part 3 Dio looks more of a fair fight, but again, Timestop + Immortality due to Vampiric Powers will put Vader in a corner too, and given the feats, Dio wins with relative ease due to his timestop.
The only fight Vader can hope to win, is against Part 1 Dio, and only if he pulls out succefully a clean cut to his head, assuming Dio lets him of course, since we're talking about the same dude who had the Space Ripper Stingy Eyes, and freezing blood techniques, if Vader reaches fast before Dio can do something, it's his win, however, if Dio strikes first, is Dio victory.
So as for most situations, Dio wins with certain ease here.