I'm super partial to Joplin. It's open source and you can keep a cloud based backup of your notes in OneDrive or other third-party cloud storage. The notes are

I'm super partial to Joplin. It's open source and you can keep a cloud based backup of your notes in OneDrive or other third-party cloud storage. The notes are all markdown which is exceedingly good for code notes, with the code blocks and highlighting. And quick to pick up. Combine with Typora for a pretty UI for your editor and you have multi-device synced notes without vendor lock-in for free. The Android app is usable but could be a little better. Desktop is solid.