Well in terms of Revan's lightsaber abilities, he did defeat Malak. Compare Malak to Darth Vader and I would say they are about equal, except for Malak being able to use Force lightning and the other is vulnerable to it. I would favor Malak in that regard.
Now as for the one on one thing, I don't agree on that. I think that their entire range of strengths should be considered. Revan was way more intelligent than Anakin or Vader ever was. He was more charismatic. He was described by Kreia like looking into the heart of the Force.
Anakin probably was a better lightsaber dualist and may have had greater potential, but turning into Darth Vader really makes any predictions to his true potential unknown. Revan had never been compared to Anakin in any degree, so without any point of reference for either character, you really can't definitively favor one over the other except with what you've seen them do.