Over the course of years, I've figured out that you have to learn to play both of these 2 programs well. Between them, they provide maximum global coverage. I typically find AA easier to redeem domestically (incl. Hawaii) and UA easier to redeem internationally including on partner airlines. There have been monthlong trips I've taken in the past where I had awards from both of them interlinked with stopovers, open jaws, etc. I couldn't have done the trips without both.

For me, the main kicker for my day-to-day travel is the fact that UA has a passable coach product and AA doesn't. As low-elite in both, I know I have to spend a lot of time in the back of the bus, although for long int'l segments I do always shoot for J awards. I like the fact that on UA, haven't to fly E+ isn't a dealbreaker - I can tolerate it. AA coach is just plain brutal.