Bear vs Obsidian
Both Bear and Obsidian are Markdown plain-text editors that can be used to link together notes.
Bear
Bear stands out as a more polished, aesthetically pleasing product with a simpler set of features. Unlike Obsidian, it is an Apple-exclusive app.
Obsidian
Obsidian is a lot more sophisticated in its note-linking abilities. You can easily build and navigate whole knowledge bases with Obsidian. That said, it's definitely more complicated and less aesthetically pleasing than Bear.
Fan of minimal note-taking apps? 🤔
Maybe Paper is what you're looking for.