Obsidian on a Mac.
Works fantastically well and uses Markdown. I use it for all my note taking. There’s a plugin for Ghost that uploads the text and creates a draft post in native format, so final tweaks can be made within the Ghost editor.
It’s worth paying for Obsidian Sync to have the same info on all devices.
I’ve also used Ulysses, but Obsidian is better in my view.