One NZ's satellite service is pointless. There would be a lot of value in being able to make an emergency call in a remote location (which modern iPhones can do anyway), but I can't imagine anyone wanting to use One NZ's juvenile instant messaging service in that scenario. 

The thing that keeps me with One NZ is the Apple Watch cellular connectivity. As a distance runner I get a lot of piece of mind knowing that I can call for assistance if I have an accident a long way from home. I don't think any of the second tier providers offer this feature.