For smaller networks and end users, the best servers to use are the ones supplied by your service provider or ISP.
First: be nice! You shouldn't synchronise to a stratum 1 server for your small network -- if everyone did that then the server would need too much bandwidth. For example. NetGear? hard-coded a public NTP server into some of their consumer products, which eventually ended up using hundreds of Mbits/second of the university's bandwidth, even after they were forced to shut down the server.
If you are running a substantial network, you should install your own Level 2 NTP servers, based on New Zealand standard time as described below.
They are FreeBSD-based servers that are directly connected to their master HP5071A caesium clock. more
There are three stratum 1 NTP servers provided by .nz Registry Services (NZRS) for network operators based within New Zealand.
All three are Symmetricom S300 NTP servers, each connected to a differential GPS antenna on the roof and each with a rubidium oscillator to provide a stable clock in the event of an issue with the GPS signal. more
Most universities restrict access to their NTP servers, however some are publicly accessible: