The best ways to fly Brisbane to Seoul, South Korea

Definitely Cathay or even look at EVA

My son flies to Seoul a lot and he prefers SQ J via Singapore. Has tried the others but likes SQ the best.

Korean Air is obviously going to be the fastest way, as it's a direct flight of 10 hours, and at least the flight from Brisbane is in daylight hours, but you're right, the A330 business class seat isn't the best experience. Cathay Pacific is certainly a good option, it has a better business class for sure and the bonus of being an on Airbus A350, but check the layover time at HKG between flights, Google Flights indicates a 7 hour layover which means a 20 hour journey, so you will spend twice as much time travelling, to me that's not worth it. Maybe you can get a better connection flying Qantas BNE-HKG and then changing to CX? Also, don't overlook China Airlines which does BNE-TPE-ICN. Singapore Airlines would be another good choice. I think in the end you will end up choosing the best flight based on your personal timetable and how long you can afford to be travelling, as well as the airline schedules.

Just flew Asiana LHR-ICN-SYD and was happy. Good seats (pretty standard for business class these days), direct aisle access and really impeccable service. Asiana lounges in ICN are nothing special but would happily fly them again (and indeed, will do, on the return leg.)

Korean Air hands down. The experience is fine...the food is very good, the seats are comfy enough, you get a good sleep if you want, plus direct flight. The service is very traditionally Korean which some might not interpret as particularly friendly but it is very efficient and accomodating. (If you ever have to make the trip in economy Korean is an excellent economy product).

Asiana doesn't fly to Brisbane, only Sydney, which leaves Korean Air as the only non-stop option.

The fastest one-stops are EVA Air via Taipei, Cathay Pacific via Hong Kong, and China Airlines via Taipei (in that order, as it depends on stopover time etc.).