Air NZ has one of the best economy and premium economy cabins in the sky – and their business premier follows on from that – it is excellent.
The easiest and shortest route would be a London – Auckland with a stop in either LA or Hong Kong – this would be with Air NZ. I’ve done the flight were my agent split the airlines. London to LA with Virgin and then LA to Auckland with Air NZ. I think you’d be able to do the same through Hong Kong.
I think Virgin has the best business class (Upper Class) of all airlines – Virgin don’t have first class on any of their flights so they’ve gone for a class between first and business with their Upper.
If you are open to airlines, go for Cathay Pacific or Singapore Airlines – they are 5-star airlines compared to Air NZ being a 4-star. If you want to stop in Dubai and Sydney, go with Emirates as you can then stop off at both. Emirates don’t have the best business class – its one of the poorest (no fully flat beds) so if you want a good business class, avoid them.
Last thing – not many know this but BA and Qantas can combine their flights so you can do a London-LA with British Airways and then LA-Auckland with Qantas but if you are doing this route, I’d go with Virgin and Air NZ. Just suggested it if you have a frequent flyer card with either of them.