I have also never heard of anyone claiming the Qantas in J longhaul has better service than Air NZ. TT its up for debate. Not even a question that it beats Fiji so that just makes me think you are trolling.
I mean, you do not like Air NZ. I get that. But you have listed some of the words top rated airlines there. Comparing Air NZ to Singapore? Yeah sure Singapore, fighting it out with airlines like Qatar, is going to beat Air NZ.
But why don't you go fly the European airlines, or the lower cost Middle Eastern airlines, or the South American Airlines and then come back to us?
As others have said, where competition exists Air NZ has lower fares. Some flights you pay more for because they are the only direct NZ connection. Take the USA. If for some reason you actually preferred the service on Qantas and wanted to fly there... Guess what? 6am flight to Aussie for you. With Air NZ you don't just pay for the flight but the amazing time that they leave. There is a lot more to it than just "service."