What is your actual destination city? Are you going to be having to race from Wellington to Christ Church on New Years Eve?

And are you currently located closer to London Heathrow or Frankfurt?

The CX flights look more desireable to me, but I don't envy a 5+ hour stop in Hong Kong. It's really not enough time to safely get downtown, and yet it's at least 2+ hours too long in the lounges. If you use that itinerary, be sure to get your boarding pass stamped when entering the first CX lounge so that you can wander around and try them all.....