Kenth was a BAMF who went toe-to-toe against Saba Sebatyne, an exceptionally powerful Jedi Master that even Darth Caedus deemed a threat. He lost, yes, but the fight was impressive.
Kazdan Paratus was insane, and was beaten by an inferior version of Galen Marek, who at that time was no match for someone like Vader. I firmly believe that nearly all of Luke's Jedi Council were at least Vader level or better. He had the cream of the crop.
I think Kenth takes it in a relatively short fight.
Vastor is very much like The Hulk. He doesn't have a lightsaber, but he was able to go toe-to-toe with perhaps the deadliest Jedi of all time, Mace Windu, and he won. To me, that alone grants him the win. Considering that Haruun Kal is Mace's homeworld as well, any advantage Vastor had would be eliminated. Mace should also have a connection to the planet.