If you like the look of some "Smart Cases" but are stuck with a Windows Phone, be patient as an update is coming soon that will give you more flexibility. The update also includes support for large screens, folder support and a lot more. Windows Phone may not be your first choice, but it very well could be a resonable choice in the near future. Hopefully Microsoft keeps the updates rolling.
Aside from previously revealed folder support, the upgrade will allow for smart cases akin to HTC's Dot View or LG's QuickCircle. Phone makers will get to run special apps when the cover is closed, and specify what happens when it's open. This seemingly simple addition could be important, since The Verge claims that HTC is preparing a Windows Phone version of the new One -- such a device would need smart cover features to perform the same tricks as its Android counterpart.