Remember Anakin is the one the prophecy is about... thats explicit without Anakin Luke would have been killed and the Sith would have ruled.
But Anakin stirred inside Vaders chest, the Anakin from the first movie, who loves his mother, and was friendly and brave. Its important to realize that everything Vader does after Episode III is out of fear and anger, he is afraid of the Emperor, he is angry at what he's done. Killing Obi-Wan didnt accomplish what he thought it would, he was trying to kill off the light inside him because he didnt feel worthy. Thats what his conversation with Luke on Endor was all about. The hint that Anakin is inside of him is only apparent on rewatching Empire and through the knowlege of the first films. In Empire, Vader asks Luke to join him, and even though we know that the Emperor told him to do it we also know he means it. (At least I do) There is a certain desperation there, and a desire to be loved.
Luke Leia and Anakin all share the same brashness, cockiness and daring that much is evident. (theres just to much of his father in him Owen) But I also think that the turning point for Anakin was knowing that luke was fighting for his family, not a rebellion, not against the emperor, but for his soul, and his sister and their family.
Thats what did it, that and almost seeing luke Turn in front of him and making the choice that he never did.
So yeah, I have a little more respect for the Anakin of the Prequals now.