I don't think there is a best one but better ones.

Personally I use Gandi when I want to pay a bit more to have a user friendly interface and support. When I just need a domain for myself I use bookmyname because it can't be cheaper and the old interface is fine for me.

If you are already sending your money to Amazon, AWS Route 53 is also a good alternative.

I've been really happy with EasyDNS over the past 10-20 years... definitely not the cheapest registrar but well worth it in my opinion. They offer several pricing plans, but I like the $40/year registration and backup mail spool. If your main MX server goes down, I believe they hold your email on the secondary for up to a week? Cheap insurance at $3/month. Been very happy with support (live person picks up the phone, and generally is an engineer). Web interface is nice, they support standard privacy screen functions for whois, and generally seem to be good people.

My only affiliation with them is as a happy customer.

I have been using joker.com for ~20 years for several dozen domains, and have never had a problem. Based in Germany, works very well.

I had the least problems with porkbun so far.