Let's see..not an impressive list compared to some of these, but at least a geographically diverse one.
Air Canada
Air China
AirTran
BA
BMI
Continental
CSA
Delta
East African Safari Air Express
Kingfisher Airlines
Lufthansa
NWA
Qatar Airways
SAS
Swiss
United
Xiamen Airlines
Best: Qatar (by far)
Dodgiest: Definitely East African, but it wasn't that bad. Plane was a Fokker 70, so not too old. Cabin service was friendlier than on most US airlines. The main issue was that the cabin smelled terrible. That's what happens when all the pax are coming from a refugee camp of 70,000 in the desert.
Most surprising: Xiamen Airlines. Very pleasant service and good food.