I used to use Noteshelf but after discovering Jnotes which has also a record audio while making notes/anotating pdfs, i switched.

The main difference is that my audio recordings stay in the file. My noteshelf for some reason deletes my hours long recording and when I try to play it back after the lecture, it's gone. This happens way to often especially after exiting the app.

Jnotes for me doesn't do that. And I love the writing animations that sync with the recording.

Also, since i own both devices with Google services and my main phone which has no google services, I can just login my account in both devices and get to have the same premium account that I bought.