I like
@lordofthereef 's breakdown! I've been on the fence, too.
To me, this year, Apple has spent more time and effort on the Series II Sport\Aluminium version. Maybe that was because more people bought that version, versus the Stainless Steel.
PS: Often times, Best Buy has the Stainless Steel on sale for $200 off. Maybe in time, that will be the same for the Series II, Stainless Steel...