If you overlook some idiosyncrasies due to its main purpose (references), Zotero really shines as a bookmark manager. It is mature and has a lot of advanced features. The last one I discovered is enabling hierarchical tags with an addon. [1]
I still welcome any new well-built alternatives like Grimoire, and I agree with you that a first-class UI is important.
I still welcome any new well-built alternatives like Grimoire, and I agree with you that a first-class UI is important.
[1] https://github.com/windingwind/zotero-actions-tags