You will be fine on AA. Save the miles and just go with them. The coach cabin on the A321s they use from JFK to LAX only have 12 rows of coach on AA and so you have a lot less people to deal with on the plane. AA has far more options from NYC to LAX in the event of IRROPs as well. This is a domestic coach flight we are taking about so it is not like you are going to miss out on your chauffeur pick up and five star restaurant food with white glove service.