Posteo Email
I've used posteo.de for my email for about four years, and I recommend it.
I can't say why I recommend it.
It's just email.
That's pretty much it. It doesn't have special features. It doesn't have problems. It's email and it costs €12 per year.
Actually, it has one feature - it has no 'Spam' folder. Instead, it has this:
Spammer: Please buy [ thing ].
Posteo: Your email has been deleted.
On rare occasions, you'll get this:
Random Person: Hi, remember me?
Posteo: Your email has been deleted.
This is fine, because the person now knows they need to contact you in some other way, rather than imagining that you got their email.