Beerman I've read through their ToS and they seem to be releasing previously taken e-mail addresses if the account is deleted (which can happen automatically if you don't pay), which is not really safe considering you might have some accounts attached to your address.
Proton Mail is alright, but it's mobile app is mediocre and you cannot use IMAP (you need Proton Mail Bridge which requires a subscription and only works on PC). It's expensive for a personal user, too.
Tutanota is OK as well but I'm not a fan of being stuck with their own client apps.
I've been reading about Posteo recently and looks like I'm going to go for it.