My experiences on AC, and I have many, mostly pre-pandemic, have been pretty awful. I would put AC operationally well below the worst of the US airlines (currently IMHO JetBlue). Flights are chronically late, staff is often clueless when they are, and when something goes wrong they are terrible at providing help (think lines of people in a terminal served by a single agent and no ability to rebook by phone). I'd take AA in a second, though as you can see there's no case I'd take AC unless I had no other option. Some of this may be informed by their terrible service in BOS; in other cities where they have more of a presence it might be better. And take it with a bit of a grain of salt because it's been a few years since I flew them regularly...