Last September I purchased a business class ticket on BA LAX to London. A week before the flight I received an email that the flight is now operated by AA. AMEX travel gave me the option of canceling my flight and getting a full refund which I declined as I was going to London for work.

absolutely the worst experience. FA were very hostile to anything I asked. The food was so bad that the only food that was edible was the bread, cheese and butter.

The only American carrier I fly with transatlantic is delta, and that is if I have no other option.