TheBrain on Linux
Well I didn't see this coming: TheBrain is now on Linux.
I've been using TheBrain for nearly 20 years. And I keep using it. In fact, the only thing that finally forced me to stop was my foray into Linux. Now that barrier is gone, so I have some thinking to do.
I can understand why people in my circles might not even consider using TheBrain. It's closed-source, it's not plain text (except it kind of is), it's weird, it's expensive, and the website makes it feel like the app isn't really for "us". None of that matters once you start using it.

As a visual thinker, I lean on TheBrain's "Plex" a lot. It's not really a mind map, but it is, except it can be nearly infinitely deep. It manages files of all kinds and does so seamlessly. It syncs with the iOS version, so I have everything there, too.
All this to say, I like using TheBrain very much, and now that it's available on Linux I am side-eyeing Emacs and things might get confusing.