Not switching from an iPhone, as I really have 0 affinity for Apple products in general, but I'm a big Windows Phone/Windows 10 Mobile fan. I find the operating system generally smoother, more modern, and more snappy than any other on the market. However, marketing and pop culture infiltration are paramount in the smartphone wars, and due to Microsoft's horrible effort in that department... the app support just isn't there. And ever since Nokia left the picture, the hardware has been uninspiring. I don't like anything about the iPhone, personally... hardware and software included.
I switch back and forth between Lumia devices, my S7 Edge and Xperia Z5 Premium. Getting a bit difficult supporting my smartphone addiction financially lol, so I'll probably be selling the Xperia Z5 Premium. I love it, and it's gorgeous in chrome, but this S7 Edge is next level. Best display I've ever seen on a smartphone, and that includes the Xperia's 4K screen. Samsung has really stepped up their game on the hardware end as well. The S7 Edge is a beauty. Can't even bring myself to put a case on it (didn't with my Xperia Z5 Premium or Nokia Lumias either).