I have never use a windows phone before, but I really love the OS. I always watch youtube videos on windows mobile and read windows central latest news.
The thing is where I live, iPhones are too expensive and the android phone I have is stuck on jelly bean.
What I like about the Microsoft strategy is their renew focus, on dedicated timely updates for their devices, which is great news. I have windows laptop and a lumia phone will complement it nicely.
For me anyone of the devices will work for me, although if I have the option I would choose the lumia 950xl as it has faster processor and size.