in my estimation... not vergere, as much as i love her... not mara... not lumiya... possibly ben...
but the two i struggle with is Jacen and Kyle Katarn...
Jacen could beat Luke by pure mastery of the Force - by bloodlines he was down as a master of the Force, if not a Jedi Master...
but Kyle is supposed to be the greatest swordsman in the Jedi Order to date... in a duel, Kyle would win...
i'm stumped...