Happy Obsidian user here. I love that the "vault" concept it uses is literally just a folder of markdown files, meaning I'm still in full control of my data. I don't use their proprietary sync service, I just drop it into a regular folder and let syncthing take care of cloning it to every device I own and a few extras for backup.
Obsidian itself has got to be the nicest markdown editor I have ever used, hands down. It gets so many of the little details absolutely right, down to tiny things like a quick shortcut to turn a list item into a checkbox (Ctrl+L) and then into a checked box (Ctrl+L again), without needing to even think about the underlying syntax. But you totally can, if you need that control. It's great.
Vaults are great. I compartmentalize all notes surrounding each consulting job as a self-contained folder/vault - that way I only have to search relevant information but still have access to it at a later time if I want to open that vault again.
Obsidian itself has got to be the nicest markdown editor I have ever used, hands down. It gets so many of the little details absolutely right, down to tiny things like a quick shortcut to turn a list item into a checkbox (Ctrl+L) and then into a checked box (Ctrl+L again), without needing to even think about the underlying syntax. But you totally can, if you need that control. It's great.