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.

Seems decent on PC, Android app is okay but there are no widgets... For a note taking app, widgets are a big deal, at least for me. I don't like having to go to the app and go through menus and what have you, I like being able to tap a widget on my homescreen that's ready to accept and save a quick note immediately, and display recent notes' titles or whatever that I can tap on to open and read. If it's going to replace OneNote or other apps, it needs widgets.