FWIW, I fly enough on both to hold both exec plat and diamond, and I think this is basically all correct.

A few NYC specific thoughts:
-If you're flying transcon on the fancy products, I find AA to be a much easier upgrade on JFK-SFO than DL and DL to be easier than AA on JFK-LAX.
-Schedule-wise, you'll be much happier on DL out of NYC, particularly if you're flying out of LGA as well.
-Before the pandemic, I'd have given DL generally higher marks for crew, but I think DL is now just as inconsistent as AA.
-In terms of airport staff, JFK is a weak station for DL and a strong one for AA, IME.