I’ve found good use of Polymail and pay $20/m for team pro. It’s a love-hate relationship though due to small but disruptive UX patterns. Some examples:

The MacOS app does not follow normal keybinding conventions. Specifically, ESC causes the app to exit full screen and cmd+shift+f doesn’t enter full screen. No option to customize either.

The iOS app will instantly show notifications for new emails, but upon opening up the app you have to wait 5-10 seconds for the emails to appear (while gmail is instant).

That said I enjoy the inbox zero image, snoozing of messages, and overall style.