I've been on 2 flights today with the following results:

GSP to DFW (737) : Had free ATT wifi. You'll see it at the top of the page on aainflight.com after connecting.

DFW to SMF (A321EOW): No ATT wifi or T-Mobile options. Apple Music workaround still works for 20 mins free WiFi. On the plane typing this now.

I did a speed test while connected in the 737, got download speeds of 39Mbps and upload at 1.1Mbps. ATT wifi does require logging in with your AA# and watching a 30 sec ad, but you get wifi for the entire flight.