In my Sisyphean search for an Evernote alternative, I periodically try out OneNote, too. For note-taking on the desktop (including on Mac), it blows the doors off of Evernote.

But, it can't search the contents of attachment files. So you can't just throw everything into OneNote and then count on being able to find it again.

In my view, this makes it a fundamentally different kind of application.