I'm trying to understand the use case where it would be worth it to switch to Obsidian and pay monthly for the sync and no longer host the data myself, which doesn't sound like an improvement to me.
The way Obsidian organizes notes sounds intriguing though, I can see how some might find that worth the additional cost (or loss of sync ability).
This is also the case with Obsidian! Because the files are just loose `.md` files in a folder, I personally use Syncthing and Git to keep them synchronised across devices for free. Sync is another option to complement those, for people who don't want to roll their own solution.
By default in Obsidian you own the data (and it never leaves your hard drive), you pay for them to host it for you so that it 'just works' across devices
That said, I've stuck with Obsidian so far, specifically because it doesn't lock me into a format. I was able to drop it on top of my folder-o-markdown & go from there. We'll see if it sticks, but so far so good.