Star Wars: Episode VI - Return of the Jedi was the culmination of Luke ... Despite all the evil that Anakin Skywalker had done as Darth Vader, Luke believed that he could find redemption.

While, yes, Vader technically killed Palpatine in Return of the Jedi, he went with ... more experienced Sith, Darth Revan would have beaten Darth Vader had they gone head-to-head.