Joplin is solid and gets the job done. I was fine with it as a OneNote alternative but once I tried out Obsidian I understood immediately what all the hype is about Obsidian. Using links instead of the standard folder structure is much more intuitive and functional for me. I highly recommend Obsidian even though it isn’t FOSS, since they have a pretty good ethos on not being locked into specific apps, and all the notes are stored in text files so you could easily migrate in the future if you change your mind about Obsidian or if they as a company do something questionable.

I’ve heard of Logseq as a FOSS alternative to Obsidian and would consider looking into that too.