https://proton.me/ is the direction I have recently chosen to migrate away from Gmail. They natively support PGP (for the super paranoid) and also has extra perks like VPN and their own version of Drive. Is it truly any more secure than Google? Who really knows, but I am tired of Google scraping thru my emails to fish out directed advertising. It would be one thing if the accounts were unpaid and this was just another way to generate revenue for the service, but with the amount of storage utilized, it was paid for (on multiple accounts). Proton provided a nice feature to import all the Gmail information including contacts and calendar. There was one oddity with importing into the calendar, thinking it had something to do with the way Google ties contact info into calendar (birthdays and such). There are many choices, even rolling your own mail server if you have the time.

On-Prem Exchange Server. Way better than anything else.

I use postfix, dovecot and snappymail. Very happy.

I already had a well-configured postfix (DKIM, DMARC) for web applications, so adding dovecot was easy. It's also really powerful, you can define who gets mailboxes in scripts. I tried going with providers but I couldn't get this kind of power.

Self hosting with mailcow.

Alternatively proton.me

Fastmail, all the way

Exchange

Mail in a box or poste.io