QF31 or QF1?

They basically leave and arrive at the same time, so choosing by schedule won't help.

When I did this trip in Y I used to prefer QF 1 through BKK because the first leg was longer than the first leg on QF 31 through SIN. Seemed to break up the trip better. Conversely on the way back I would go through SIN to get the long leg over with, leaving just a (relatively) short hop down to SYD.

In J, though, it would depend on how well you sleep. Taking QF 31 through SIN gives a bigger uninterrupted chunk of sleeping time on the leg into LHR. If you sleep well on planes this could help you to adjust to British time better. If you don't sleep well, you may prefer to go via BKK to make the two legs closer in duration.

 

I personally wont go via BKK ever again - but I am not a big fan of Thailand. Do you have lounge access? The lounge at BKK gets crowded I hear and the SIN lounge (when I sneaked into the F lounge) was very nice.

 

Fair point - do you have the option of flying via HKG on CX?

 

I wasn't very impressed with the BKK Flounge or the airport itself. It all looked quite modern and new, but quite sterile. BKK Flounge food wasn't anywhere near as good or extensive as SIN Flounge food either. (But it was quite quiet despite some delayed flights.)

I didn't mind the SIN business class lounge either, although I haven't been in the BKK equivalent, so I can't make any comparison.

So if all else is equal, maybe lounge differences would be worth considering.