Luke Skywalker. Because he brought balance back to the force (with a little help from Anakin) with only a smidgen of official training. He was really a Jedi autodidact.
Yoda is the daddy, but Obi-Wan has the best scenes, especially the death-sticks scene and of course, 'Why do I get the feeling you'll be the death of me' to Anakin.
Yoda - he's just the coolest little green guy ever. Even better than Kermit (yes, I know he wasn't a Jedi). Or Anakin/Darth Vader because the bad guys have teh best lines.
Dear lord, how I'm going to suffer when Revenge of the Sith comes out. The burden of dating a geek ^_^