My last iPhone was the 3GS. I switched to the Note 1, just for the inking. I'm now on the Note 4 (saw no added value in the Note 5), and was waiting for the Note 6. When I first went to Android, I lurked on XDA-Developers, and while I never installed a custom ROM, I was amused by the attitude of "the Apple fanboys only want a phone that works", referring to the lack of customization. Well, that's me. I want a phone that works, along with functionality.
Of the three operating systems, for me, Android is by far the worst. My favorite is Windows mobile, specially for its integration with Windows 10. I have a 1520 and an 830, both wonderful devices. The problem is the lack of apps. How can you take an operating system seriously when there is not a native Starbucks app.
I find Android to be clugey - I am certainly able to find my way around it and make it work, but I don't find it to be elegant.
I went over to the closest Apple store last evening and picked up a 6S+. So far it has been a seamless transition, and I've found iOS to be as easy to muse and as functional as I remember. All my important apps are there, and, as they said over on XDA developers, "it just works!"
Ron