I really like using Fastmail. For raw features, it's got a contact sync, calendar sync, custom domain suppport, a snappy webmail client, push notifs (which Gmail does not support outside the official app), a robust spam filtering language, integration with 1Password that lets you make per-site masked email addresses, and a lot more.

As for security: I only care about account security, not confidentiality. As a friend said to me recently "as far as I'm concerned, emails are digital postcards". For account security, Fastmail has 2FA and revocable per-client passwords.