Proton is somewhat ok, better than Gmail at least. And their encryption is solid, but that's just for the content. Plus when you pay for their service, they can connect your email accounts to your real name. Metadata (times, dates, recipients etc.) is not encypted. You can also have that level of encryption with any self-hosted email and PGP. Proton just makes PGP easier to use.

Better forget the idea of a secure email service, it's an old flawed service. Use encrypted chat clients instead. I do nothing sensible with email.