Be cautious with Quad9; their main address (9.9.9.9) has a "malware" blacklist that has misfired several times already: twice for a private torrent tracker, once for gist.github.com, issue was resolved within minutes to hours. They have a non-filtered address (9.9.9.10), but it doesn't do DNSSEC verification. IMO they're too unreliable to be worth the hassle.
This is great, thanks for the correction! I tried resolving dnssec-failed.org and it does indeed fail with EDE 6 (DNSSEC Bogus). I'm not sure why this hasn't been updated on the info page[0] yet, given that the change is about three months old.
It's fine when it's a non default option. Like use x.x.x.x for DNS, x.x.x.y for DNS+adblocking, x.x.x.z for totalitarian corporate blocklist that doesn't let you do anything fun
I believe cloudflare only blocked archive.is on their "Families" filtered dns. I've been using their normal 1.1.1.1 and haven't encountered any blocks.