I just recently came back up from a deep dive through knowledge management systems, and Trilium is what I settled with. It might not look like much on the surface, especially compared to the bling and hype of the VC baked alternatives, but once the basics click (everything is a note, notes can have inheritable attributes, you build types of notes like in OOP inheriting from base notes by leveraging the hierarchy, instances are just notes that have a template relationship to the model notes and can be stored anywhere), it's a damn elegant and powerful tool.

Definitely underrated/highly recommended!