Apple Mail (macOS)
No-nonsense but full-featured email application for macOS that works well with multiple IMAP accounts and Gmail. Features an “All Inboxes” view as well as showing each account individually. Setup can be a bit weird since parts of account config are in System Settings. Uses the system Contacts application. You can add and remove server folders on your accounts. Better than Windows 10 Mail, not as good as Thunderbird, but lighter and snappier.