I am not from NZ nor UK but have lived in both countries for more than 10 years each. For me personally the good things about NZ are:
Sunshine, beautiful rich blue sky, yes it can rain often in Auckland but it comes and goes quickly, you still have so much more sunshine and nice temprature than UK, and a long warm summer
Amazing wildlife, I used to wake up with tuis singing outside my windows, I have spotted colour parrots coming and going in my garden
Easy to grow your own vegies, they just thrive without much attention needed due to the climate
Clean environment, I hardly needed to wash my car
friendly people, people are laid back, the gap between the rich and poor is much smaller than UK
Amazing beaches, landscapes you can access a lot of stunning places in such a small country, campimg is also very safe
Better health care system than UK in my opinion, never had to wait long to access health care
Lower taxes, from memory 33% for high earners
Student loans and living allowancea were offered at 0% interest rate for life if living in NZ, not sure if its still the case now but at least it was when I was there
House buying process is so so so much more efficient than UK
Paid sick days, I had 10 paid sick days a year plus annual leave when I worked there
Great vineyards and NZ wines but European wines are expensive and not many choices
What not so good are
Food are expensive and lack of choices, specially European food products
If you love shopping its bot a great country, lots of brands arent available
People can be narrow mineded, specially the ones who have never been out of NZ
A lot of national pride, you see the word "proudly" everywhere, too much for me
No proper lunch for school kids, everyone brings a packed lunch and often eat outside sitting on the ground
too isolated, far from anywhere, even to Australia is still a good 3 hour flight