Great blog post looking at Microsoft’s OneNote on the Mac.
There is a version of One Note for iPad at: https://itunes.apple.com/us/app/microsoft-onenote-for-ipad/id478105721?mt=8
One Note is developing a lot of momentum with the announcement that Microsoft have developed an assignment feature on Moodle that allows you to submit OneNote pages (https://moodle.org/plugins/view/assignfeedback_onenote)
More posts on OneNote:
The latter post explains how you can utilise the file extension feature on the iPad to share a range of different resources onto OneNote on the iPad