Obsidian

I've used Obsidian for a couple years. It's a very good note-taking app. Vault (a paid add-on) makes syncing across devices effortless, but other cloud solutions also work. Composing in markdown's fast: your hands never leave the keyboard. It stores notes in markdown, so there's no lock-in: you can open them in a text editor. Once a note is synced to your device, you can reliably get to it even when you're offline. Quirks are in tables (a bit clunky) and the outline (hard to find on phones).

If you know, you know. Obsidian is possibly the best thing for keeping info that you'll ever try. It is for me. Incredibly generous program, and the mobile app is just as good. Used to be slow for me. I learned not to stack 1000's of mixed files (zips, exe's, full program folders) in your vault, and it's fine. much quicker now, on top of that.

LOVE THIS APP! My go-to app for anything writing related. Highly customizable, super easy to use, 1000s of community created plug-ins that allow additional functionality, tons of awesome looking (& customizable) themes... I could go on all day. I also have this on my PC and I can seamlessly sync between the two with 1 tap/click & be able to continue EXACTLY where I left off on the other device by installing a plugin. End-All-Be-All of markdown/notebook apps!