Within the past month I've done PE/WTP on a couple LHR-JFK trips. Despite my reservations about BA currently being an operational nightmare, solely in terms of what's on board I'm finding I prefer BA. The main factor is that the BA seat feels like it reclines to a noticeably greater degree, so I slept much better on the BA segments. (I'm comparing BA 772/77W and AA 77W.) The catering is six of one half dozen of the other - the first meal is better on BA but the second meal is better on AA. The IFE is a lot more extensive on AA.

For me the seat comfort is the decisive factor, but I can see how other elements might swing to AA for others.