What does HN recommend as a better Win10 email client? I'm familiar with Thunderbird and I'll probably switch to it if nothing else, but I'm not a huge fan of the UI/UX.

I use Mailspring which is available for Windows, Mac, and Linux. I use the free version but they have subscription model with many features (which I don't necessarily need).

https://github.com/Foundry376/Mailspring