Not being open source is the great... sin for me. Note taking is an investment in the future, and betting on a closed source platform is a big no no—for me, that is.
I know the content is safe in Obsidian, since it's just Markdown files. But the workflow? Not so much.
And I know the developers behind Obsidian have their reasons to close source it. Nothing against that. But since that's their way, it's not my way.