It also depends on how far 'out of the way' they want to go to get the best First service. UA PS and AA's 3 class domestics generally fly the JFK-LAX/SFO routes.

If TPs are your thing then AA do a single flight number one stop flight BOS-SEA stopping in ORD - it is on an MD83 though. There is no IFE on these birds but this looks like it might be changing see here

I have only flown UA and AA domestic First flights and I would say they are on par. Both can have great crews, both can have so so crews.
The food offerings on AA have improved over the last year after the serious declines they took after 9/11.

I don't mind the AA F seat on their two class domestic aircraft. As Traveloguy says it is larger and far more comfortable than anything you get in Europe.

Why don't you take a wander over to the Trip Report forum in the Community section and see what you can find for the different carriers.
Some of the reports are quite detailed and often have pictures of seats, food etc.