My feedback is that this is a push. I prefer the 757 generally for the reasons mentioned above, and generally I'm a big DL fanboy, but most of my flying is DL and UA with very little AA experience.

If you really want to split hairs, take a look to see about seatback entertainment if that's important to you. Likewise the DL studio offering.

Now if cost isn't a big issue, I'd suggest you route through JFK/LAX. That would be a whole different ballgame as the service between those city pairs is like international business class. In that case, I'd rank AA first class > DL "One" > AA business class.