I haven't been down to NZ for a couple of years. But I enjoyed flying Qantas. Firstly you can fly Emirates under the Qantas codeshare, which if you're flying the upper classes also gives you access to Dubai lounges etc. You still get full tier points etc even if it's Emirates metal.
You also then have the options of the Qantas metal flights either the 787 to Perth/Melbourne or A380 via Singapore. I also quite enjoyed Sydney airport, if you have status the first class lounge is pretty awesome.
Alternatively there are the Qatar airways options. Or there's BA to Sydney, then transfer to Qantas for the last sector.
Not sure if helpful but thought I'd share
