SC earning is the same on all airlines and strictly based on sector length and class (the discount economy classes vary by airline, but D is the same for all of them). From the east coast the BA J product is a mixed blessing (flight is too short to get much sleep, so you don't get much use of the bed, though BA has tried to fix that by not serving dinner on-board and offering pre-flight dining instead). AA has better food eastbound, and the 763 J is a J+ service (midway between J and F). Definitely worth seeking out a 763 flight to FRA, also the extra 2 hours flying time to FRA makes the flight a lot more pleasant.