If you're going to pay for email, why not Google Workspace (formerly G Suite)? Their paid service is entirely different to the free Gmail service. For instance, on the paid platform, your data including emails are not scanned or parsed in any way by Google (for targeted advertising etc...). Your data is your data. When it comes to email these days, you basically have two choices, Google or Microsoft. Sure there are smaller players out there, but your experience/mileage may vary. Both Google Workspace and Microsoft O365/Azure Commercial Cloud are on the US Government's Federal Risk Management Program authorisation list and many Government entities around the world use services like Google Workspace. In Australia, Google Workspace has IRAP (Information Security Registered Assessors Program) certification (I'm pretty sure Microsoft has it too) which isn't something that is handed out willy-nilly. I figure if it's good enough for Government agencies handling protected and secret information, it's good enough for me.
Remember, if it's free, you're not the customer, you're the product.