I'm trying to decide whether to do NH/NZ lhr-nrt-akl or UA/NZ lhr-sfo-akl. Now on the surface, the former would appear to be the obvious choice. I say 'appear' as I've never flown UA or NH, and am reluctant to make a judgement on an airline I've never flown. However it just seems that UA has a desperately poor reputation from a vast array of sources.
So, my hesitation in choosing the NH option is that the flight on their equipment will be the longer of the two sectors and is a proper night flight on slanting lie-flats (I'm not sure if I'd manage to sleep at length at an angle). My thinking is that going via SFO means essentially a day (ergo, I'll stay awake) flight on a seat that I would hope is pretty comfortable for lounging in, with a LHR based crew that, by all accounts, seem to be generally rather pleasant. I then would be connecting to NZ's superb horizontal C seat at a time when I'll be ready to sleep through the final (longer) leg to AKL.
However an important 'pro' for the NRT option is that I imagine it is a far,far better INT-INT transit experience than SFO (although I understand that SFO is pretty good by US standards). On both options the transit is around 2 1/2 hours.
If you've got this far and understand my ramblings please feel free to throw in your opinions/advice