https://en.wikipedia.org/wiki/Public_recursive_name_server
- Google
8.8.8.8,8.8.4.4,2001:4860:4860::8888,2001:4860:4860::8844: Private and unfiltered. Most popular option. - CloudFlare
1.1.1.1,1.0.0.1,2606:4700:4700::1111,2606:4700:4700::1001: Private and unfiltered. - CloudFlare
1.1.1.2,1.0.0.2,2606:4700:4700::1112,2606:4700:4700::1002: Private, block malware. - CloudFlare
1.1.1.3,1.0.0.3,2606:4700:4700::1113,2606:4700:4700::1003: Private, block malware and adult content. - Quad9
9.9.9.9: Private and security aware. New player that blocks access to malicious domains. - OpenDNS
208.67.222.222: Old player that blocks malicious domains and offers the option to block adult content. - Norton DNS
199.85.126.20: Old player that blocks malicious domains and is integrated with their Antivirus. - CleanBrowsing
185.228.168.168: Private and security aware. New player that blocks access to adult content. - Yandex DNS
77.88.8.7: Old player that blocks malicious domains. Very popular in Russia. - Comodo DNS
8.26.56.26: Old player that blocks malicious domains.
Additional reading: https://freedom-to-tinker.com/2018/04/02/a-privacy-preserving-approach-to-dns/