I considered both before choosing one. Ended up going with Protonmail because:

* The folks behind Protonmail are also heavily involved in the OpenPGP.js project. Interop with plain PGP from non-Protonmail accounts is on their roadmap and a feasible future feature. AFAIK that's not on tutanota's roadmap and they use a different customized crypto library, so all you'll ever get is e2e encryption with other tutanota users.

* Proton's mobile app is a top-rated android mail app, and pretty good even compared to iOS's Mail app.

* IMAP support is also on Protonmail's roadmap, but not something I miss due to the good mobile app.

* The tutanota.com and tuta.io domains are dorky and hard for other people to remember.

Thanks so much for pointing this out. I had never heard of it before and had a look. It looks good and has a team whose values I identify with. What's more, it has flexibility in billing that looks quite attractive (users, storage, aliases, etc.).

Unfortunately, it does not support IMAP or POP, which I prefer just to have local copies of mails as a backup.

A paid account looks appropriate (and would help the company stays in business), but it's a bit pricey for my needs (though not as much as other providers who don't have a lot of flexibility on users/storage/aliases).

I will try the free account to experience it firsthand.