I have flown business longhaul MH twice recently.Service on all sectors was great.
As our home airline QAN has a pretty good reputation and daughter recently travelled BNE/NYC without complaint in economy If you are travelling business then price would be a major consideration.
Personally I would fly direct to the US if travelling economy and not even consider MH. You may pay a little more on QAN but the time saving far outweighs the dollars spent.