I agree with all the above posts – the new AA business class is miles ahead of BA’s. However, I am afraid I don’t agree with Tim’s advice about row 4 – the window seats are offset so that they are actually next to the galley.
Also, do not be put off by the poor lounges – remember that oneworld rules allow access to any oneworld-airline-operated lounge of the same class. This means that if departing London (LHR T3) you can use not just the AA lounge but the CX or BA lounge, irrespective of your FFP status. However, the lounges at DFW are very poor (regardless of airline!).
Not only is the seat superior, but the in-flight snack bar on AA is superb, and I have found the food quality generally higher than BA (and the warm nuts and ice cream sundaes deliciously tempting).
Crew – well, consistently inconsistent. So nothing really to choose between the airlines on that front!
Overall, I would opt for AA in a heartbeat.