I fly mostly UA, but have flown AA transcontinental and trans-Atlantic in the last year. I find their in-flight service to be weak - once the FA's have done the meal and beverage, they tend to gather in the galley and chat, looking at passengers as "intruders." This is true even in business class - they rarely came around with water, for example. And when I went to get some on another flight, she pointed to the pitcher on the galley counter rather than get up and get me a cup, etc.

BTW, many of my domestic flights on UA this year have been coach, as have ALL my international flights, so that doesn't account for the difference in service that I perceive.