The difference is staggering, and no one that I know of prefers to fly U.S. airlines unless they absolutely have to. As someone with lifetime status and a current EXP on AA, I hate to say it, but my experience in Y on a recent low fare trip on Korean Air was so much more enjoyable than my flights in C on AA or BA. I was dreading sitting in Y for international flights, but I didn't have to be. The seats were spacious with plenty of legroom, the equipment was new with working IFE with a good selection of movies and shows, the FAs were polished, efficient, friendly, and nice, and the food choices were tasty and there were many offerings of snacks. My companion and I were both very pleasantly surprised at how much we enjoyed the flights, in transpac Y, at a level that I've never experienced on any U.S. airlines in Y (and in some C).