Originally Posted by Kacee

UA is a more functional airline right now - more reliable, much better app and IT overall. While it's not notable for outstanding service at the gate or inflight, IME you're more likely to experience truly unpleasant service on AA. UA also seems to attract a more professional, law-abiding customer base, at least here on the west coast. They also haven't torturized their domestic cabins to the same extent as AA, and as Gold or Silver, you'd likely be able to score an E+ seat on most if not all flights.

I was originally driven away from UA by their ridiculous PQP qualification scheme, and you might want to take a look at that to see how it squares with your travel patterns. Though who knows if they'll ever return fully to the published standards. Value of the frequent flyer miles is also low and dropping, if that's important to you.