Update to my experiences re: S Note, OneNote, etc...
It's my finding that design-and-performance-wise S Note for Android is the best handwriting note taker overall (I've used them all on all platforms, mobile and desktop), but syncing to and from it's Windows app is completely broken. Also, Samsung's sync server is often down, producing messages about how it will "be back soon". Samsung won't comment on it. They did say in an email to me that they'd refer it to the right people.
Having never looked at OneNote before, I found the Windows version to be surprisingly well done, practically on par with S Note. That is, IF you are using the Windows version, though I find inking/drawing in Windows S Note oddly quirky, dim ink, non-smooth lines, etc. And, sadly, the Android versions of OneNote are not fully baked with the same feature set -- for example, at this time (late January 2015), OneNote for Android does not seem to be able to open a PDF for annotation -- one of the important features I look for, and present in S Note -- an important feature for business / real-life application of the tools. Several other features missing in the Android apps (compared to the Windows app) also become quite noticeable in use.
However, OneNote's long term advantage is cross-platform accessibility, and it's promising design as seen in the Windows version so far -- so it's probably the best choice in the long run. S Note's "cross platform" experiment, so far, is a failure, which is unfortunate. And of course, who knows if a Mac or iOS version of S Note would ever see the light of day, another shame if it doesn't.
All that said, I'm still at this moment in time using S Note for Android, not syncing (successfully) with Windows S Note (running Windows 7 in VMWare on Mac). My efforts with OneNote, so far, have been less than satisfactory for reasons mentioned above. iOS will never amount to much as a note taking tool -- though I've used it for years for that purpose -- because it has a capacitive screen requiring the blunt-force rubber tipped styli that are a ham-handed pain to use due to their inaccurate inking.... Samsung's Note series of devices (I have Note 4 and Note Pro 12) rock the Casbah in the note taking category.