Proton's being a bit slow and weird is totally worth it just for the privacy features. And it's slowly improving with time.

I can suggest having a look at Infomaniak: https://www.infomaniak.com/en/ksuite/service-mail

And with the kSuite, you have everything: file storage, chat, emails...

I have no involvement with the company, except as a happy customer for many years

Well you can try Proton for free and see for yourself.

I've noticed that people either care about email being efficient and private, or they care about the comfortable bells and whistles of their existing inbox (and Gmail has many), but you can't really tell which one you are until you test something new for yourself.

I'm happy with tutanota.

It's extremely minimal though. I think it's just mail, contacts and calendar.