I have flown American Airlines and others, many of them defunct such as Eastern, Panagra, Mexicana, Pan Am, TWA, Brannif, PSA, AirCal, Western, Continental, America West, Aloha, Western, Capital, Trans-Texas, Southern, etc. etc. For years, AA was pretty good and had routes I found convenient. As others died or merged, I consolidated much of my flying to AA, but continued to use other airlines if cheaper or more convenient. I had top status for over 1.5 decades, and am back to middle lifetime status — that grants me guaranteed services on AA and alliance flights. But I continue to fly other airlines that are cheaper or more convenient, e.g. Alaska, Southwest etc. when it’s more convenient. And though AA is IMO more variable in its services today, no US airline stands out for consistent exceptional service. Or maybe ever exceptional service, for mid-level to no status passengers.