After testing three secure DNS services - Cloudflare, Quad9, and NextDNS - it seems Cloudflare has better speed resolving queries, than the other two, at least here in Tauranga. I expect if I was closer to Auckland, that would change.
I am keen on NextDNS due to the wide range of settings and blocklists available. It seems to work well. I wonder if there are any other secure DNS offerings with a variety of blocklists as NextDNS has, that might be worth trying here in NZ? I'm not super fussed about speed, so long as there _is_ actually a NZ-based server.