After spending many hours in the sky with Asian Pacific carriers (Thai, Malaysian, NZ and SQ), and then many hours on American carriers, the US carriers are the worst in the free world. On a recent NWA flight I felt guilty for asking grandma for a coke. Even if age is not a factor, even the young attendants on domestic services in the USA seem like they hate their job.

For European carriers, I love the KLM folks. They seem like they work so little but they are almost always happy and look like they enjoy their work (when they get around to it).

Long haul USA carrier worst flight crew in my books goes to NWA.