Oh god....
Well, obvious ones out of the way.
Luke: Really good character growth since the beginning of the original triology, dude went through a lot losing both his mother and father just after being born, and living a really bland and uneventful life style for the rest of his life until a new hope.
Dude doesn't get everything handed to him on silver platter, sure he's talented, but he still had a ton to learn even after his long and arduous training with Yoda.
I'd like to point out in the original version of the Empire strikes back, after the twist we all know. Luke fell down the shaft but DIDN'T scream, this to me communicated that he doubted he was going to come back alive, but felt he had no reason to live anyway, but I'm probably nitpicking.
This man kept going, and going, and going, and going, never going down, always getting back up, until he did what had to be done, and is the only one to bring someone back from the dark side.
Darth Vader: This is honestly self explanatory, many Star Wars fans still hate the prequels even existing and say what you will about them, because of those prequels we got many other interpretations of Anakin in the micro series and clone wars series. Which enhanced Darth Vader's character more.
Ahsoka: HATED her when I saw the terrible Clone Wars animated movie, loved her in the clone wars series, and while a lot of people talk bad about it I do intend to see Rebels through to the end.