1- Yoda. And that is mostly because of how Vader/Anakin's image has being degenerated over the years. After the PTs, I cannot see that character the same way. Also, there are a few discrepancies of how the character behaves on ANH, TESB and ROTJ, that have bothered me. Yoda was also buthcered on the PTs, but his essence remained the same. While having little screen time on TESB, and VERY little screen time on ROTJ, and being a freaking puppet on Frank Oz's hand, he had such impact and was such a great character, he became a myth as itself. Therefore, Yoda is my choice. His use of the force lifting the X-Wing is more of a valuable moment than Vader force-chocking people.
2- Luke. This was VERY tough, but the justification came easily. Luke was able to achieve what Obi-Wan wasn't, the redemption of Anakin and the fall of the galactic empire. Also, Luke is a character who has progressed in such a way during the OTs, that it grew bigger than Alec Guines's character.