Well quad9 isn’t that bad:

Primary DNS: 2620:fe::fe Secondary DNS: 2620:fe::9

best I know is 2600::1 and 2600::2

This is very interesting. One of the reasons I like nextdns is because of the relatively short addresses. 2a07:a8c0:: and 2a07:a8c1:: but this is even shorter. I always felt like sprint should’ve put a DNS service on 2600:: feels like such a waste not to.

If you ever need an easy one to test for E2E IPv6 connectivity then 2600:: works too. Useful to remember.