I think the Android crowd has reached some kind of plateau. Since the Galaxy S3 there was only upgrade in raw numbers, no real new features that I see any use in. It's similar for the iPhone, nothing really special there either.
That's were I see a chance in Windows Phone. Because they are still lacking in so many areas, they can really bring an upgrade that makes sense, bundled with some nice new hardware. After all I realize more and more, that a new Windows Phone would certainly be easier than switching to iOS. Not because of the apps, I use not many of them and I could easily afford to buy the counterpart on iOS, but because the Skydrive, sorry Onedrive, is implemented well, and because Exchange synchronization just works perfectly.
I don't know about Exchange synchronization on the iPhone though, maybe it's just as good.