I did a lot of analysis paralysis and comparisons when I was looking for a very low cost provider that works with my own domain so I can get off Gmail and avoid future vendor lock-in. I wanted 100% standards compliant email hosting that will work perfectly with an actual, old-school email client workflow, plus some sort of web client I can fall back on if needed.

I also wanted EU or Canadian hosting and a non-US corp I'm sending my money to, plus lots of online indication they have been reliable for many years and have generally very good community reviews. I don't actually see the value in the provider-based encryption of Proton/Tuta and think it creates a false sense of security because there is basically no reasonable threat model where their system seems to actually protect you - okay, come at me ;)

In the end, it was down to Runbox and Migadu. Both are 20-ish bucks a year with my custom domain and satisfy all my requirements. Migadu seemed very good, and comes with more storage space, but I prefer to migrate my archived mail off the mail server over time anyway.

Runbox has a really slick web client, doesn't have the silly-low 20-email-a-day sending limit, and the clincher for me was that I can add secondary accounts on my domain for $8 a year! I may actually make some accounts for family on my domain at that price. I switched the domain over to Runbox a few months back, and regret all the time I procrastinated doing it.