I've flown from London with Etihad, Emirates and Qatar. I thought Qatar was the best, most comfortable seats and shortest stopover, only one hour. Actually on second time I used them it was only a few minutes. The flight from London was late getting in and we had to run through the terminal to get to connecting flight to Bangkok which was held until we boarded.
Also the second leg from Doha was fairly empty so I got a row of seats to myself.
These days I prefer direct flights taking only 11-12 hours and go with Eva, Thai Airways or BA whichever is cheapest - usually Eva.