There should probably be a deadpool board that lists all the registrars and lets people bet on which will be the last ones standing. I am going to guess a couple of the last ones standing (that still have something resembling technical staff) will be Amazon and Cloudflare and to be clear I did not say anyone can reach their technical staff.
Whatever the consensus will ultimately be in this thread this week will probably be registrars we perform libation for in the coming years.
The only downside is that they use Cloudflare DNS behind the scenes, so when Cloudflare goes down, your website goes down too unless you use third-party DNS.
You can always use third-party DNS if that's what you wish to do. That should be a supported configuration with ~any registrar (and if it isn't, avoid them).
You can run your own (first-party!) authoritative nameserver(s) for your domain, if you want to, and you can even do this on hardware that you can see and kick. A nameserver isn't particularly hard to set up in a sensible fashion.
However it happens, eliminating Cloudflare's DNS from the equation is easy. The TLD nameservers (for .com or .net or whatever) will cheerfully direct resolvers towards whatever nameserver(s) you specified as part of your domain registration.
After that, when Cloudflare DNS dies on any random Tuesday afternoon, your domain will still work. (Maybe it won't work for those using Cloudflare's 1.1.1.1, but those people may have bigger issues on that particular Tuesday.)
Edit: I feel that it's pertinent to point out one of these experiences that were particularly bad. About two years ago I tried to register an IDN (internationalized domain name) with them. The registration succeeded according to their interface. Money was deducted. The domain did not appear in my inventory. My support ticket took several days to receive attention and was just closed with the almost arrogant response, "you probably did some mistake", with no further information or support. My second support ticket, too, took several days to get a response, and it was then revealed that the problem was that they weren't capable of registering IDNs under that specific TLD, for unknown reasons. That support ticket was also closed without allowing me to respond, so I had to open a third ticket just to get my money back.
I know, Amazon isn't super cool, and are imperfect in a bunch of ways. But at least it appears to be highly configurable and cheap, and Amazon ain't gonna get bought out by private equity and enshittified, legally bullied into oblivion, generally has pretty good quality and competent support, and has plenty of experience in not handing the keys to your castle of services to any random phone caller with a sob story.