I've flown both products recently and can say that there is little difference between the two. For an O/D pax with no status I would book based on price (incl. seat sees if BA) / schedule. Any carrier can be late, any carriers can have bad crews, etc. Both BA and AC on TATL are fairly middle of the road long haul J products with latest generation reverse herringbone seats, edge to BA for the door, edge to AC for slightly better padding and footwells. Catering on both have been meh - again, middle of the road.