Themes was the least important issue for me, easy of use was much higher in my list of priorities.

Being able to easily create and pack themes is meta-important. That is, a good set of themes cannot appear by a community effort unless creation of a theme is reasonably easy and well-documented, and themes are self-contained and easy to share.

And I'm quite the opposite. If your SSG comes with prebuilt themes and a ton of deep integration overhead (like Hugo) I'm going to pass. Just give me RSS, blogging, ability to use any templating language, and I'm good to go.

Sure, having good existing themes is important, but it's much harder to quantify.

Also, themes are not 'one size fits all', so consider meeting your local designer/frontend developer (or contact me :) to create a theme or at least adjust an existing one. It makes quite a difference when the theme fits to your needs.