I'm not sure if it's exactly what you're looking for since I never used either it or OneNote myself, but Microsoft Word has a "Notebook View" which might answer your needs.
Omni Outliner Pro can be good for taking notes in class (depending on your subject).
You can attach documents, images, pdf's, audio recordings etc to your notes.
I think the non-pro version is free, so you could give it a try.