I've flown AA a fair amount lately. I agree with your assessment, except it should be noted that in my experience United's wifi is cheaper than AA's, sometimes significantly so. On a route I usually fly, wifi is either $7 (A320) or $11 (737) on United, while AA wants around $20 for the same flight.

I'd say 80% of the time the UA flight attendants I encounter are very pleasant, about on par with AA.

I find UA's reliability of operations better than my recent experience with AA. UA is no stranger to delays for ridiculous reasons, but my experience with AA is worse (3 mechanical delays just in the last month). Note that this is a recent improvement for UA -- it was far worse in the last few years.

The UA app is a step change above the AA app, and you can do a lot more self-service with UA's systems (upgrades, same-day changes, etc.). UA's app also allows me to better predict when irregular operations might occur so that I can switch to another flights.

One significant downside I find with flying paid F on United is that when things go south, it's difficult to be accommodated in F on an alternate flight day-of because F is often already full. This is different from my experience with AA, which seems to have more F seats available close to departure.

I have zero experience with Delta. I would put UA above AA in my experience.