NameCheap for the ones they support. I don’t like how tightly wound Cloudflare domains are with the account. I’m nervous about putting too many eggs in one basket with them. I sometimes need to switch hosting a domain in a cloudflare account with another cloudflare account. They don’t let you do that without moving a domain to a third party registrar first. I just shortened that process.
the correct answer I think is cloudflare? I'm a little wary of internet homogenization like this but I haven't the time to worry about this sort of thing for my spare one-off domains