Kylo has none. The difference between Vader and Kylo is that Vader believes he had no choice. He was absolutely manipulated into a situation where he (wrongly) felt like his back was against the wall, and acted accordingly, and found himself in a place where he basically is left with nothing BUT Palpatine and his Empire to sustain him moving forward. It's only when the son he never knew he had pokes his head out of the ground and has the temerity to still believe in him after his botched seduction to the dark side that he starts seriously questioning who and what he is and why he's doing it.
Kylo's had multiple chances to go back to the light whenever he wanted. Nobody forced him to go dark. He just did it. And even after he did it, it's been made apparent he could come back. He just doesn't. He's a man who has refused prior redemption even though his parents are STILL putting their hands out there for him to take. And then his father personally approaches him with yet ANOTHER chance at redemption - and he kills him for it.
They're on different arcs entirely, and at different places in those arcs at the beginning of their respective trilogies. Vader basically understands that he bought his existence with his actions, and dedicates himself to making the most of that, so the sacrifice isn't meaningless. Kylo is all about racking up meaningless sacrifices in an effort to prove to himself he's the tortured, evil, powerful man he wants to be.
Vader had his redemption because someone showed him the door that he didn't know anyone could open. Kylo's always had an open door. He just keeps slamming it shut.
No one wants to see that kind of motherfucker get redemption. They want his ungrateful, stupid ass to catch the punishment he's begging to get. And I think that's going to be the conflict for some of our main characters: What do you do when the person who still has something worth fighting for isn't interested in your better interests, and refuses to let the light in? Again - he's a combination gambling addict/school shooter here, basically. And he's already stood by and watched as five planets blew up, and that's before he murdered his father. None of which he had to do, and he knows it. He's an unstable individual who talks to the burnt helmet of his dead grandfather, whose life he willfully misunderstands.
What kind of satisfying redemption do you come up with in answer to that?