Are there any redemption arcs/stories that you've found that actually did a good job with the issue?
There have been a few.
The obvious go-to that just about everyone thinks of when they think "good redemption arcs" is, of course, Zuko from Avatar.
As deuteragonist of the series, his patterns of belief and their impact on his behavior are put under a microscope pretty much from the get-go. The story takes tremendous care to examine what he believes, why he believes it, how hard it is to break away from it, and how fulfilling it is to finally let go of the toxic incentives that have guided him.
People have been trying to reinvent Zuko for years with mixed results. Often overlooking that what made Zuko work was that we really truly got to know him as a complex and nuanced human being, inside and out.
I'm also partial to Scarlemagne of Kipo and the Age of Wonderbeasts. This character is a lot more despicable than Zuko, but we get to see him broken down psychologically over the course of the third season.
Rather than going straight from villain defeat to redemption, Scarlemagne spends much of the third season in prison having philosophical debates with protagonist Kipo. During this time, not only is he able to express and examine his system of belief, but she gets to express hers - ultimately converting him into a true believer in her own methodology over time.
By the time Scarlemagne officially becomes a protagonist, it's only on the back of watching him develop and change from the confines of his much-deserved prison cell.
For a Star Wars example, since Vader was where I started ranting about redemption today, there's Agent Kallus of Star Wars: Rebels. Kallus starts out as an Imperial officer and recurring villain until a Bottle Episode strands him and a Rebel protagonist, Zeb, into a survival situation together.
The whole episode is spent hashing out Kallus and Zeb's different perspectives. Kallus doesn't come around during these talks; By the end of the episode, they go their separate ways and Kallus returns to the Empire. But having this time to debate belief systems with Zeb plants a seed of doubt in Kallus. He begins questioning fascism in ways he hadn't before, ultimately bearing fruit when he becomes a secret Rebel informant - rightfully assuming that no one would trust his intel if they knew who he was.
Also partial to the entirety of The Good Place and My Name is Earl, both of which are shows centered around questions of morality, personal development, and redemption - and which both examine the topics in great detail, despite being very different tonally.
man why couldn't i have some cool special interest?? i got the autism that makes me like a tv show that got cancelled well over ten years ago and has a severely dead fandom and a horror comedy trilogy from the 80s to 90s about some transgender sleazeball with a chainsaw for a hand. both the main characters? severely bisexual and transgender.
One of my favourite character archetypes is the character going through a redemption arc who has been bad for so long that they've forgotten (or just flat out never learnt) how to be good.
So, instead of being "good" in the typical way, they use their view of how the world works to try and be good in a way that makes sense to them.
It's just really neat to me when media can recognise that good intentions can come in any form, even when a character doesn't go about acting on them in the expected way.