So I went with DNSimple after looking at a few different companies. Initial experience is good, I like their ethos, and their support is friendly. Here’s a referral link if anyone is interested (we both get $5 credit if you sign up).
My DNS is all now managed with #Terraform (this provider), stored in Git, with the Terraform state file in Nextcloud so I can safely edit on multiple machines. They have good APIs so all sorts of automation is possible if that’s your thing (hey, it's 2018 - it should be your thing!).