I've cancelled my subscription yesterday, conveniently it was about to renew at the end of the week, so I have a few days to migrate from Proton, here's what I'm thinking of, but I'd love to hear what other people are switching to
Love mailbox.org. Had it for 5 years at this point. I have a custom domain, and a wildcard address, so anything before @ goes to my inbox. So whenever I sign up for anything I use a unique email. This way I know both where mails are coming from, and can easily block any compromised email addresses, and update my password. Good stuff!