Still trying to find a good one myself. Tried using Evernote but their code formatting isn't that great and I'm always worried about the day they might close shop.

Been writing Markdown files in a git repo, then syncing on Gitlab so I'd have them accessible anywhere, but there's more manual effort involved with writing Markdown (I forget some of the fancier list/bullet formatting) and also defining metadata for future lookups (first few lines of each text file).

If someone made an Electron-based app, this would be great for all the programmers out there.