I recently switched to Posteo from a few years with ProtonMail. Reading from Purelymail's docs and with price being within $3 annually of one another (Posteo is €12 annually)

Posteo pros: comes with calendar and contacts via WebDAV, not registered in the US (Germany is part of 14 Eyes, but not 5 or 9, and the EU is better about privacy), cash payment option

Purelymail pros: more storage @ $10, custom domain support, security key 2FA (though unclear according to docs if this is WebAuthn/FIDO2 or Yubikey vendor lock-in)

Neither: cryptocurrency payment option