I've found InternetBS and Namesilo decent. Used to run a domain related service with thousands of domains and used about a dozen registrars. Older ones tend to have poorer support and dated UIs, the two I mentioned are fairly young and I've had no issues with them.

Been using name.com for many years without complaint. Cloudflare is also good if you are already using their DNS and they support the TLD you want.

Been very happy with Namecheap. That is maybe not saying terribly much, having moved from GoDaddy (arguably one of the worst out there).

I have some at Gandi, for some years now, stable service, good API, straightforward web interface.