
Koodo Reader is an all-in-one ebook reader that can help you better manage and study your ebooks. It's free and open-source.
Tried to import a folder of all of my epub books. It did not load my folder properly. I then attempted to drag a single epub file directly into it, and it did not seem to work. I'm not a big fan of the UI, but if the software worked I'd be able to excuse this. Nonetheless, the apparent lack of epub compatibility means I have to strongly recommend against trying this reading software.
Ît has a lot of options, looks modern. But I couldn't make the two page mode work well, at least with epubs.