Hacker News Reader

I have been using FairEmail for a month now. It's privacy centric and has loooooots of features. It is ad-free. It does not open stuff that may be used to track you by default. It can do GPG and so much more. It is developped by a single and very responsive developper for now. I liked it so much I bought the premium version to support his work but paid features are quite niche and you won't click on something only to find out that you need the paid version. https://email.faircode.eu/

I use "K-9 Mail"

If it was available on the desktop I might actually prefer it over Thunderbird.

Feature wise its a far cry from what Thunderbird can do.

I used to use Aqua Mail when I had a slow phone which could not run Gmail that well. Now a days Gmail app is good enough. If I use third party clients, the email search does not work as good as Gmail. So there really isn't any option.