I currently host domains with the following registrars:
- Cloudflare Registrar - At-cost domains, but limited number of TLDs
- Porkbun - Cheapest one for most nTLDs
- INWX - Cheapest one for my .de and .eu domains
- OVH - Cheapest one for one .se domain I own
I only consider registrars, when they meet these requirements:
The cheapest registrar can often be found via tld-list.com.