There must be quick support available, in case of locked account.
Outlook, Gmail, Protonmail, Fastmail..?
Apart from that, redundancy makes sense - don’t rely on a single email provider/service but have several independent email identities with your mail synced across them. This goes for associated data too - the worst part of having your account locked is losing access to your cloud-stored contacts, files, etc.
I love Gmail/Cal but don't trust Google's long term offerings. Fastmail means I have my mail in two locations.
mail.com is a bit heavy with the adware. gmx.com has more free options (like mail forwarding).
Dunno about support. I'm not recommending, just mentioning.
1: Use your own domain, this allows you to somewhat easily move providers. 2: Offline backup of your email. Keep a offline backup of you email, it could just be a desktop client checking email. 3: A paid provider with support, so you can get to talk to someone.
I personally think icloud is a option. Fastmail or hey.com could also be.