Vader's definitely more powerful than Maul. In a showdown between the two Vader would kick Maul's ass. Vader's got the highest midiclorean count of all the Jedi's ( including Yoda ). Maul may be more acrobatic and show off some Kung Fu shit, but that's more an issue of filming ... the early Star Wars movies were filmed more than 20 years back and film making techniques then cannot be compared with what it is now ... if the early movies had been made today, I bet Vader would have been shown to be a much more formidable and powerful hand to hand combat fighter than he was shown in the first 3 movies - and he would have come off even scarier and darker. In fact I bet in Ep.3, although his basic appearance will be the same, he will be shown in a really more darker and terrifying way, much more scarier then Maul could ever hope to be - kind of Darth Vader year 2005 version. After all he WAS responsible for the almost total destruction of the Jedi - I think in Ep.3 he's going to TOTAL Mace Windu in single combat.
Not true.
GL has stated that the prequel era sabreists are better fighters, and are fighting the PROPER way.
In the Original films, all three fighters are hampered in some ay. Obi-Wan is old and his skills have lapsed, Vader is slowed by his crippling injuries and armour, and Luke is half-trained.
Maul IS better.