Call me an Apple-hater, but the iPhone is NOT that good. Maybe it has good hardware, horrible iOS. It's simple, yeah, because it can't do anything!!! I also found its Settings very difficult to use. I have an LG G4, and I love it, and although I do wish it had a better battery, I can easily switch it when it is dying with the spare LG gave me for free. On an iPhone and Galaxy S6, you can't even take off the back.
And Nexus is nowhere to be found...
Also, as someone else mentioned, security is extremely important. iOS and Windows Mobile 10 both have great security, except from the companies that made the OS themselves (Apple and Microsoft). Android has fair security, but much more vulnerable than the other two. I would say BlackBerry wins in security, even with the Priv.
I am considering going back to a non-smartphone. The one I had, the Pantech Matrix, still works great. Battery lasts for 2 weeks at a time, no need to deal with annoying touch keyboards, no security risks except from the cell phone company spying on text messages, extreme durability without a case, no expensive data plans, and super simple OS. And fast!
I'll just keep using my LG G4 as an MP3 player of sorts, but I'll usually use my Surface 3.