AA is very ht or miss...
My experiences in 40 plus Round trips to and from Chicago/Miami/Dallas en route to San Jose and Medellin. This does not include many domestic flights on AA as well. Random guess on the amount of legs I have flown on AA over the past 4 years, I would guess it has passed 175 if you include domestic flights.
1 delay longer than 2 hours, this was on a MIA to ORD flight that we were forced to sit on the plane for the 2 hours while they fixed the plane, we finally took off, made sometime up in the air and landed at home about 1:25 late.
1 delay longer than 3 hours, boarding was delayed due to a plane coming from the east coast in the dead of winter. No a big deal as I just hung out in the Admirals club.
No other issues. I do not count anything delayed under 30 minutes, as the scheduled arrival times are always 30 minutes later than actual flight time to keep their on time records in tact..

I am very lucky I know, but as usual with the airlines, Your Mileage Will and always does VARY !!!
Probably jinxing myself with this post, but it was time to pipe in... I have had very good experiences with AA. If I had my choice, I would still prefer flying Taca (cuter flight attendants) but there routes have declined for my preferred destination...
As far as the planes go, I am no expert on aircraft, but I have always flown either an MD-80 to Dallas, a 767-300 or 757-200 to Miami and always a 757-200 from Dallas to SJO or Miami to SJO and MDE, again with minimal to zero real major issues.
solo mi dos centavos....