I've used Fastmail for many years now, and I have nothing but good things to say about the service. In particular, it's insane how well notifications work in Fastmail, especially compared to Gmail (which I use at work). (Honestly, you'd think Fastmail was the giant multi-billion-dollar super-advanced tech company, if you look at the quality of their email experience vs. Gmail.)

However, some folks are a little spooked by the privacy implications of it being ran out of Australia, so be sure to research that if you're interested in Fastmail.

I'm leaning toward Tutanota, but I can't claim to have experience with them yet.

Proton has appeared somewhat bumpy to me -- I can't say for sure why, but they give me some spidey tingles.

Migrating / transferring is indeed a problem. I would suggest using Google Takeout, their data export tool, and permanently archiving your data with a third party service and / or physical backups. See https://takeout.google.com/. You probably won't be able to import into your new provider.

Thanks for this, I didn't realize you can actually export all your data from Google.

ProtonMail isn’t supported by iOS’s default mail app, which for me personally meant I hardly used it. It’s just too much hassle for everyday email.

I ended up trying fastmail and found the transition much easier.

If you own a domain through Gandi (possibly others) you get email included for free. This is what I use. I don’t know why I don’t see this recommended more often?

I would do this through bluehost but it just straight up doesn't work. No matter the tutorials followed or time spent with support, I can't receive emails at my domain.

Migadu is great because they bill based on emails sent rather than billing by how many accounts or domains you have.