To me the big difference is in operations. IMO, UA has improved quite a bit and AA had really dropped over the last 2 years. But that could change again 6 months from now if AA is trying to do anything to improve.
All of the other differences are likely to come together, meet in the middle, at some point over the next year...totally my opinion of course.
It's interesting you're looking at connections. Out of ORD, I rarely connect anywhere in the U.S. Most places I fly domestically (maybe 20-25 destinations per year) I can take nonstop flights on UA. When I travel internationally, I can connect in Europe (ORD-FRA/MUC/BRU) or Japan (or SFO). Perhaps you need to connect more on AA, or it has to do with the partner network?