Staff that are unfailingly polite, comfortable seats in all classes, well maintained interiors, a culture of excellence. It is an airline that competes on being the best experience possible. My FIL used to do a lot of business in Singapore, and exclusively flew them on any route that was possible mostly economy and business class, but a spend that was high five figures per year, in the top tier of whatever their points program was. A staff member who knew what he looked like would meet him at the curb and walk him into a private check in cubicle. Even if you aren't one of their frequent fliers, they just treat you far better than you can expect from EU/NA airlines.
US mainline carriers try to get the high end travellers in first class, while also trying to run an ultra low cost carrier with the new "basic" class tickets. They end up doing a mediocre job at both by not hitting the level of service that Asian airlines provide, and not having the low prices that the Ryanair's of the world give you.
US mainline carriers try to get the high end travellers in first class, while also trying to run an ultra low cost carrier with the new "basic" class tickets. They end up doing a mediocre job at both by not hitting the level of service that Asian airlines provide, and not having the low prices that the Ryanair's of the world give you.