10 email aliases in Proton Mail Plus and 15 in the Unlimited account are far too few. What’s the point of paying for three domains if I can effectively only use three email addresses per domain in Proton Mail? Whether it’s Startmail, mailbox.org, or especially TutaMail, the number of aliases you can create with your own domain is significantly higher—or even unlimited—everywhere else.
I can't switch from Tuta because I only have 10 email addresses here, one of which is the Proton Login address and another is the postmaster address (elsewhere, administrative addresses like postmaster or webmaster don't count at all).