If you want something very, very basic...but something that spans all platforms, try Google Keep.
https://drive.google.com/keep/
If you've never heard of it, it's because it's brand new...like a month.
It's no One Note, and it's no Evernote, either, But it is simple, free, and works flawlessly.
For your PC, including Surface, you'll use your browser. For the Android, since it's Google, there's obviously an app.
No idea about an app for iOS, since I no longer play in that yard. But my guess would be the Google-Apple feud would make that a 'no.'
Again, though - very basic. But personally, I like it and use it several times a day.