Domain Provider
I use Cloudflare to purchase and host all my domains (for cold email and websites). They are trustworthy, have excellent performance and reliability, a great user interface and many of their services are provided for free.
I also use Cloudflare to host some of my websites (e.g. Baconaholic, Cornish Flora and PerformIT), with their free ‘Cloudflare Pages’ feature.
If you just want domains and don’t need other services, there are cheaper providers (e.g. GoDaddy, Namecheap).
If you are already ‘invested’ in other services/providers (e.g. Google), you might want to use them to host your domains.