Vader was a much worse person.
What feels so odd is that even though this point holds absolutely true upon objective analysis, I can’t help but on an emotional level, feel that the redemption of Kylo would feel incredibly jarring and not right.
I attribute this mainly to the fact that within the OT, (not counting dead children from some awful prequel movies) we only see Vader murder random people who we never know all that much about. In Rogue One, it’s a dynamic of him just being a “badass”. Kylo Ren on the other hand murdered Han Solo. It just sits differently for some reason.