The 763 J is probably AA's most controversial product. Some people dislike the fact that AA went through some silly cost-cutting by not including in seat IFE which is frankly ridiculous. But I personally like the 1-2-1 parallel design and the seats are actually some of the most spacious and comfortable around especially if you pick the right ones.
Food on AA J and F has improved significantly in the last 6-12 months and meals are often very good. On my last flight, a pan seared snapper was both enormous and delicious, and my partner's Korean short rib was too. On my outbound, I had a rack of lamb that was both better and much prettier (remarkably well French trimmed for those who have a good butcher's!
) and had the great advantage of not swimming in some silly sauce which is one of my main complaints about most airline food. My partner had a salmon with red thai curry and grilled king prawn, again excellent.
To be honest, if I am to take AA or BA, product-wise, I give the edge to AA on most planes in J, and to BA on most planes in F. I also choose by times, convenience, fare, and if all else is equal lounge, so that gives BA a benefit ex-JFK (JFK CCR is nicer than the renewed and improved Flagship, even though Flagship now has better décor, Champagne, San Pellegrino soft drinks) but AA an advantage ex-MIA where I prefer to use the Amex Centurion lounge. Indifferent ex-LAX where I can use the QF F lounge for both, so AA wins on the planes if in J. ex-LHR, BA used to have the edge thanks to the CCR in T5, but the CX F lounge in T3 is actually very nice and the forthcoming QF lounge may well be too.