I think Carr may be a bit better than Winston but mostly just because Carr does not throw as many YOLO balls as Winston. But Winston also makes some off schedule plays that Carr can't so it's close to a wash.
Personally I would have kept Winston and looked for a young QB in the draft while Winston was starting. If you can reign in Winston's dumb throws he has a lot of talent to be good. Payton was on his way to doing it but who knows if Winston would have continued on that path.
But this notion that some have (not you) that Winston was going to keep playing for backup money is absurd. If he was brought back as the starter instead of Carr, he likely would have wanted a contract similar to Carr. Not that I blame him. A starting QB should get paid like a starting QB. And even if he signed on a backup level deal if he any success they were going to have to give him a Carr/Mayfield level deal.