From what I understand, he stopped Hitler's inspections of his crew to weed out Jews. He protected his crew from the Nazis and behaved in a reasonably honorable fashion given the circumstances.
I'm trying to think of individual sub commanders. Most of them were telegenic guys who wound up as folk heros back in Germany. Two Officers were a big deal if my memory serves right. One had blond hair and a movie star attitude, and one was just a kick ass Officer.
Arioch7 out.
This Captain got his damaged sub off the sea bottom near Gibraltar. Well it was a good movie.
Donitz was put on trail for the same things American submariners were doing to the Japanese. He was no Nazi. Why Hitler put him in change after his suicide is anybodies guess.