Maybe I've just had a string of poor crews on AA (or unusually efficient ones on BA), but my impression is that BA’s express meal both arrives quite quickly and also arrives faster than an AA meal. For regular (not express) meal service, I suspect AA is faster. However, this is all just impressions. Next time I’m on appropriate flights, I’ll need to channel C-W-S and time the service on a stopwatch to get a proper comparison.