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).

the app is really great. I'm giving four stars because when I download community plugins, after some days they all just disappear and I have to download them again. (Update) After some Reddit research, I found out that this problem is because my phone automatically clears junk files everyday, I disabled the feature and now the issue no longer exists.

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.