Does Kinect not count as a hardware differentiator? For this reason alone MS has the be the favorite among dedicated game boxes.
Nintendo's been the most innovative historically but they've already shown their hand and sadly for them it's holding a ginormous controller that I'm 97% sure is a refurbished Sega Gamegear.
The only question left about Nintendo is who wins the exclusive rights to Mario/Link and co. It's probably worth the most to Microsoft but Apple has a lot of cash overseas they don't know what to do with.