The last time I flew it was with American, the time before United. Given a choice I don't fly (because of the TSA caca) but also given a choice I'd refuse to use either big carrier again.
Once a year I flew to St Louis for one customer, a weekend job. Most years it was fly out Friday morning, return Saturday night, but sometimes the project required staying through Monday; I always booked a late evening return flight. And, until this year, if we got done early (and we usually did) I'd get to the airport before 2PM on departure day, and they'd always accommodate me on an earlier flight. I had a ticket, they had spare seats, why not? I have to check a bag (tools) so the fees were annoying (but covered).
This year American said it would cost $90 to get on an earlier flight. That would not be reimbursed by the customer... so I had to sit out almost 7 hours at the airport. The agent was very apologetic but said it was absolute policy and she could lose her job if she tried to slip me on an earlier flight. Flights in both directions no longer provided soda or snacks (but were priced 40% above last years). Checked Bag fees were also higher.
I was seriously peeved.
I took all the info and (after I cooled off a week later) wrote both online feedback and a typed and signed letter to AA customer service, and the office of the CEO. I got an auto-acknowledgement from the online submission, and have heard nothing else back. I imagine they get so many complaints they don't even bother to respond any more.
(I wrote my senators about the groping at O'Hare too, never heard back from them either)
OTOH I now have approval to drive for that trip

Its about 5.5 hours each way so a win.