It has a significantly better UI than Calibre, no question. I only use it to manage my ebook library and send them to my various Kindle email addresses. I can’t compare any more advanced features because I didn’t use them in Calibre and I still don’t in CW.

I gave up on FOSS alternatives and journal exclusively in Obsidian. it’s not open source, but the file format is simple text files. Which for me, was a must.