I had to fly UA when AS cancelled my Sfo - Ord flights last minute. It’s been years since I’ve flown them and I admit it was much better than I expected. Planes were cleaner than Alaska and service flow was efficient and standardized. Alaska FAs seen to just kind of make things up as they go along - sometimes it’s great but often it leads to very slow or uneven service.
Seeing as how Alaska is now on its 5th month of meltdowns this year there is no reason to think it’s going to get better. I’ve moved most of my summer flying away from them.