Having done long haul with both AA and BA in both in econ and econ+ : avoid AA in economy unless you have status or are willing to pay extra for their MCE (main cabin extra) seats. Seat pitch is essentially the same in econ on both AA and BA (although I was happily surprised last week in a refurb BA 777). In WTP the products are similar. The big difference are the crew. Despite the, dare I say, decline in BA offerings, BA still outshines AA in service delivery (AA literally throws the food at you with a scowl).