__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk
I'd go with Muur. Sure, Wyyrlok is a great sorcerer, but Muur really impressed me, he was powerful enough that Vader worried about his spirit taking control.
We didn't get to see much direct combat of Muur, but we know that he was rival of Baron Dreypa, who was a badass, and he was able to catch, augment, and throw back Krayt's force lightning so hard it gave mortal injuries to the Master who was stabbing Krayt in the back at the time!
So in short, Muur'd win a lightning war, sorcery I bet on Muur too, and physical it's hard to say but Karness was good enough to be rival of another physically powerful sith.
Well, I've found out that there's a quote in Insider #113 which confirms Karness Muur's superior power over both Darth Krayt (who is canonically more powerful than Wyyrlok) and Cade Skywalker, so the Force round really isn't debatable anymore.