One thing I've always found so interesting about Vader's ultimate redemption is that it's all about his capacity to love his family. Nothing about peace or justice or realization about the state of the galaxy or the force, just that he turns his back on the authority and institution he's served for two decades to prioritize and save a person who he feels attached to, who means more to him than all of it.
Sound familiar?
From that perspective, it's no wonder that Obi-Wan and Yoda couldn't sense the good in him. There wasn't any, by any Jedi definition. Only in the definition of "any capacity to love=good". Padme knew this much, because she knew even fallen Anakin loved her and would have done anything for her. Luke knew, because he could (truthfully) sense that Anakin Skywalker would do anything for him as long as he knew that Luke was his son.
It's just always been so interesting to me that his redemption was through the same vice as his fall. (Insert "jojo have you learned nothing". meme). He wasn't redeemed in a grand moral sense, just back to the same Anakin Skywalker that was willing to do anything to save the life of those he felt belonged to him, no matter the cost. 20 years as a sith didn't shift his values an inch.
