I gave AA several chances in 7 flights in a 3-week period. It would have been 8 flights and 12k miles if they hadn't bumped me making me take another airline back (as a business traveller I cannot afford to "come back tomorrow" most times). There wasn't a single one of those flights where I didn't see endemic problems with AA. The ground staff is a mixed bag like most airlines but organizational structure to make it work despite the incompetencies and inefficiencies is very poor compared to most major airlines.
Examples of good/bad service practices:
EWR 5AM: AA counters for London flight. Four desks open two for first class, two for coach when I came in. Two of them yawn and leave within 5 minutes (the airport only opened at 4:30Am!). The remaining two stop processing any coach and only process first class passengers leaving the people in coach line left wondering for 20 minutes. No supervisors or helpers near the queue in sight.
UA (or most other airlines for that matter): At least two desks each open for coach and first class. Helpers near the queue answering questions directing people, checking paperwork and passports, etc.
Example #2:
AA extra security check: The 20 or so passengers selected for secondary screening near the gate are made to wait in the jetway standing (no chairs) after screening for 15-20 minutes or so before the plane is ready for boarding. Not allowed to go back to lounge, of course. Remaining passengers sitting and sipping coffee in the lounge in clear view of the "specially chosen". Checked-in baggage search: Check in after standing in line for 30 or more minutes like all other passengers. Accompany to-be-checked in baggage to a special area after this. Wait for the processing in another line (20 minutes) and the go to boarding.
UA extra security check before the check-in: Selected passengers searched before check-in are led to a special counter for expedited check-in processing (faster than the Elite/Business class line). Two approaches to the same requirement. One smart and another dumb.
Just some of the bad examples I saw of AA.
This is not meant to be a "tastes great, less filling" debate between AA and UA (or CO or any other airline). Just my observation that AA as a big airline has a serious structural and management problem that does not promote consistent good service. Saw many things like this during the UA decline of the early 90s.
Cheers