As a student returning to school in September my most important need
would be staying organized. There are a lot of classes to keep track of
and a ton of work for each of those classes, and chances are, you forget
(almost happened to me way too often...
In all fairness, it depends on your budget. I would recommend the S9 as
it is IP68 rated (dust and water-resistant) and has pretty good
hardware, plus it's now heavily discounted. S9 is currently the best
"bang for your buck" type of deal.