I took AA F LHR-LAX a few years ago and while it was not as good as QF F, I was reasonably happy (have to say though I am not usually too difficult to please), though the second 'light' meal - some sort of turkey roll IIRC - had something in it I really did not like. Serves me for not listening to the description properly. The individual seat layout is sort of similar to QF on the 380 but older and not as automated (though 1-2-1 instead of 1-1-1). IFE was reasonable (watched the entire LOTR trilogy). After I had to request a second glass of red at lunch, I could not stop them refilling the glass (well, eventually I had to otherwise I would have rolled off the plane).
I have not done a similar trip on BA so cannot compare, but I cannot imagine it being that much better (but someone else may have a comparison).
The AA Flagship lounge was lower in standard than the BA J lounge in T3 (in fact, lower than a domestic QP) - IMHO of course. The flight was a daytime one.