~~Tuta and~~ Posteo are both pretty excellent (posteo is cheaper, but has a few less options that might be a deal breaker if you need them, like custom domain support).
Disroot is a good free option, and they offer custom domains after a one time donation.
Mailbox is okay, though they are known to have a very odd 2fa, and will recycle your address if you ever stop paying, allowing others to claim it and potentially impersonate you.
Posteo is unique in that they'll never delete your account for inactivity, or even if you stop paying, where they'll let you access and read emails, but not let you send them until you pay again.
Edit: apparently Tuta is going downhill according to others here, which is unfortunate :(