Namecheap

A domain name registrar should do the following things:

• have good registration/renewal fees

• support many TLDs including those you plan to use

• provide Whois Privacy (for free or at nominal cost)

• have a quick and logical administration interface

• allow using third-party name servers

​Namecheap checks all those boxes for me, so I've been using them for a long time now.

​Cloudflare has also entered the domain registrar business and I've experimented with using them too. Currently not enough supported TLDs (specifically country codes) to use it exclusively.