Neither are particularly secure because you cannot trust proton or tutanotas 3rd party encryption, only your own PGP key. But it is possible to register for protonmail over tor from their .onion site. You may need to restart the browser a few times to get a clean exit node. Once one gets blacklisted by too many people registering from it, they take away the captcha and force you to enter some sort of identifying info, but it can be done with a little persistence, I have a couple. This is the most anonymous you are going to get, it is very difficult to find email services you can register like that, I'm not aware of any others that wont get automatically listed as spam if you try to email someone.

As long as you only access that account through your tor browser, and keep identifying info out of the messages you can probably safely assume you are anonymous. If you want secure, just use gmail and PGP, but keep in mind that any messages that arent sent to you from people encrypting them on any service are visible to that service, even if you encrypt all your outgoing messages, which would require all your recipients to have PGP keys as well.

If you really need both anonymous and secure, you probably shouldn't use email at all. Something like Signal or similar registered with a phony number is your best bet for that