I'm sort of half switching to AS because I'm flying at least once a month to PDX for the foreseeable future. I'm stuck with some time on UA because they're a preferred airline for work so they often come up cheapest, though not always. I managed to fly an LAX-BOS RT last week with UA out and AS back. The difference is pretty dramatic - I managed to get a premium seat on the AS flight (and had E+ out) so got whats left of the VX MCS service before they discontinue it. I also got upgraded both flights of LAX-PDX RT this weekend as an MVP. As a perpetual silver I have low expectations, and haven't ever really had bad experiences on UA so much as there's nothing exceptionally good most of the time either. Consistent E+ at T-24 is about as positive as it gets. The only place they really stand out is IRROPS, as long as you have any status at all. I fly Delta infrequently and my experiences with them are consistently bad - if you don't have status, IRROPS is about what I'd expect from the worst of the old NWA.