You have a pretty good grasp on your situation. Tough choice but a great one to have.
AA reserve can be good. Narrow body and live close to airport can make huge money. I just had a trip with 5 different FOs. One was killing it living in base flying overtime over guarantee. One made $100,000 more than me last year. He lived near the airport. Dropped flying and did overtime. One was like me just flying our schedules. One flying out of base. One trying to fly as little as possible on short call reserve. The options are endless.

Wide body must be really really good because it is hard to get. Junior Captains were hired early 1990s or earlier if you were not originally AA.

I can’t speak for United but AA culture is bad. Angst among all the different factions of previous airline mergers. That should slowly disappear as all retire. Now we have the young hating on the older.

Robert Isom hates pilots with a passion. I don’t know why but it trickles all the way down through management.

I did some overtime fling in November and still haven’t been paid. We are constantly having to fill out forms to get paid. We pay $10/month to a third party APP to audit our pay. Every month so far I have had to correct my pay. My conclusion is that they do it on purpose. Hard to like a company that steals from you every month. Why APA can’t take this service over is my question.

Reassignments happen all the time. We do not get any extra money when this happens. They can fly you way past your original trip completion time with no extra money. They can also fly you into days off but then you get some OT for only that flying into the day off.

AA work rules are way behind. Not everyone thinks this but everyone who worked at an airline before AA thinks this. Just had trips with a JetBlue and Spirit pilots. They are amazed at some of our crap we deal with. The JetBlue person is having real doubts about their choice to leave. Spirit guy is hoping it gets better. I told him I have been hoping the same thing for decades.