[OliveMate]

I tried it out for a while, I'm sure that it's a great program and it's various free sync options & encryption system may immediately put it ahead, but as a basic user I found it much more complicated to the point where I couldn't figure out how to simply sort files into folders (and I don't know if that's something you can do). There's an interesting tagging system to search posts with and there's a ton of plugins out there if you want to do things you can usually do.

I really ought to give it a shot again when I've got a clear head.

If you want a FOSS alternative to Obsidian that's just as simple you could try Zettlr, but currently it's rather rough. You have to change the UI settings to get the folders/file view that Obsidian has, and I found readability to be rather poor. Initially there's no way to make in text larger without zooming in the entire UI, font, and the themes that are available aren't the best for writing or reading notes (and if you like one specific theme you're sod out of luck if you want a darker version of it) – if you want to change things to your liking you have to experiment with the experimental Custom CSS option.