As a commuter, I end up on Delta a fair amount of the time (and Alaska).
Delta THINKS they are pretty hot stuff....not really a noticable difference in economy.
Alaska has great customer service....if they could fix their seat pitch thing. And you do get treated well in 1st.
The laughable thing is that they brag that they have the "most room in premium" of any legacy airline.
(I honestly thought I was in coach at the time, the seats were so cramped.)

The handful of times I end up in the back of an AA flight (usually deadheading), I really don't see any difference between them and Delta.

Now, our 88 year old FAs that are going to work until they die..... Who thought that was a great idea?