I've been a 1K for years, but last month my employer switched to American as their preferred carrier, so I've just started to fly AA.
My initial impressions have been very positive. AA Customer agents and FAs uniformly seem genuinely friendly and helpful, compared to my hit-or-miss experience on UA.
But my biggest surprise was on my second trip. On the day of my return flight, I checked my office voicemail to find a message indicating that my flight was cancelled; requesting me to call and arrange an alternative. My wife, at home, also received a call.
Seems like a simple thing; but in all my years with United (and MANY cancelled flights), I cannot recall ever having received a courtesy call.
I'm beginning to think there IS a difference between airlines...