Welcome to Flyer Talk meremaiden

I haven't flown V Australia but between Qantas and Air NZ, Air NZ has the much better economy product (at the moment).

More legroom (especially on 747 up to 34" vs 31" on Qantas), more consistently better service, better IFE. If you are flying after December then watch out for Air NZ 773 aircraft - these have skycouch (more space for a couple but at a premium) and also smaller regular seats (narrower and less legroom).

Note that all 3 airlines also offer premium economy with better seats, food and drink; but at a much higher fare than regular economy.