You will get a lot of different replies here. Everyone has a favourite.
For me, I prefer Etihad or Qatar Airways, short stop in the Middle East, very competetive pricing , comfortable and reliable.
Others prefer Thai or Eva direct to BKK, some like Emirates stopping in Dubai en route.
A lot of people prefer going via Singapore with Singapore Airways, a very good carrier, but no use if you want to go through BKK.
For independant reviews of airlines check out this site
Skytrax Airline and Airport quality ranking and global Passenger Forums