I'm sure Revan was probably the most powerful Jedi I've heard of. Although I could be wrong, and I know people are going to argue against me.
Each Dark Jedi and Jedi alike, each have their own strengths, Revans being his military smartness, and possibly his skill in both force and lightsaber combat.
I personally think Revan could kick Vaders, Sidious, Grevious', Mauls, Malaks and Bastilas asses at the same time. Cause he's awesome like that
And Starkiller don't stand a chance against Revans power
Starkiller was indeed powerful, although not as powerful as many, but Revan knew many dark and, sometimes, terrible things about the dark side, having discovered them on his journeys to discover the Star Forge
The only person I think that could stand a change against Revan is POSSIBLY Yoda
Yoda is strong in the force and all, but, really, he's old, and he doesn't have the strength of many other jedi in battle.
Darth Caedus was pretty powerful as well, he could manipulate the past using the Foce.
Even Kreia herself said that looking at him was like looking into the heart of the Force.
You can't deny that he was extremely powerful.
More powerful than Vader, definately.
Vader wasn't that strong, really
By the way, does anyone know a link to a list of Metachlorian counts? (sorry if I spelt that wrong)