[s777]

For the free versions, they are pretty similar, except ProtonMail supports PGP which works with people who don't use ProtonMail, whereas Tutanota uses its own encryption which only works with Tutanota users. Neither of them support third party clients (although ProtonMail has an IMAP bridge for desktop for their paid version), so I would say ProtonMail is better for that reason. Both of them are much better than Gmail though privacy-wise.

However, one thing to be careful of is that unlike Gmail, neither of them support email forwarding, which might become a problem if you want to switch email providers again. A workaround for that is to buy your own domain and use the paid version of whichever service you choose so you can change services without changing your email address. For that feature, Tutanota costs significantly less than ProtonMail does.

If you want an email provider that is more focused on features like Gmail but doesn't sell your data, you can also look at FastMail (Australia) or Mailbox.org (Germany). FastMail (what I use) has a better UI, but it is based in a country with anti-encryption laws. While ProtonMail/Tutanota are trying to be government proof by end-to-end encrypting your emails at the expense of features, FastMail/Mailbox.org are more focused on productivity without making money off of your data. To me, FastMail/Mailbox.org have good enough privacy since I use Signal for most personal communications I want private, but if a government is after you for some reason, ProtonMail/Tutanota would definitely be a better option.

[aborsy]

Fastmail is the opposite of the ProtonMail and Tutanota in terms of privacy and security. I wonder if it’s much different from the paid version of the Google’s email (where, I suppose, users’ data is not commercialized either).

Protonmail uses OpenPGP, so it better interfaces with other services.

[s777]

I'm not sure how paid Gmail handles data, but at least Fastmail is not from a giant ad company that wants to basically DRM the internet with WEI and generally has an incentive to collect as much data as possible and show ads everywhere. Privacy (against corporations) is one of Fastmail's main marketing points, and considering how it's a smaller paid-only service where being discovered lying about its claims could basically destroy its business, I would trust it more than paid Gmail which will continue to exist despite Google's unethical behavior. It's not end-to-end encrypted though, so it's not perfect privacy-wise, and worse than ProtonMail/Tutanota in that regard.

However, after looking some things up, I just saw that Mailbox.org has a feature called "Encrypted Mailbox" that automatically encrypts incoming emails before storing them (which I somehow didn't see when I was using it since I thought it was similar to FastMail but based in a different country), similar to how ProtonMail/Tutanota work, and I'm not seeing anything similar for FastMail. However, Mailbox.org also supports third party clients and features that FastMail has like email forwarding, unlike ProtonMail/Tutanota, so Mailbox.org actually looks like a better option than any of the others (assuming you trust that they're not secretly storing your emails as they arrive somewhere unencrypted, although they might if forced to by the government).