By appropriate we mean the one that is the closest match for your community of interest. Whilst the DNS was never set up as a directory system, Internet users assume some implied correlation with the second level domain used. Before applying, you need to be aware that registration involves the collection of personal information about you and your domain. This information will be publicly available through the Domainz Internet web site. Provider is to manage the name application from the customer viewpoint and liaise with Domainz to get the name listed.
Provider also collects important information for Domainz in order to list the name on the Internet.
The .nz Provider will usually provide name service, too. This should not be an onerous task, but those responsibilities are important in order to ensure continuity of Internet service to a listed domain. The last point to make relates to payment of fees. Provider fees, or Domainz fees. All Name Holders should be aware that fees need to be paid in order to register, and keep, a name listing.