Long time protonmail subscriber and reasonably happy, but them not allowing SMTP access (other than through proton bridge which is a GUI app - workaround: https://ndo.dev/blog/headless_protonbridge) kind of sucks, and their search functionality is also not great.
I agree on the search functionality. Even the apps do feel a little clunkier than Gmail. Considering how much I get for my Proton subscription I doubt I'll look for an alternative for a while. They're mild annoyances really.
Debating moving over to Fastmail as well