Here's my case for iPhone being the superior device for 2017
Since Google is such a questionable company these days, and since Google services are baked into android phones out of box (barring root, F-Droid, and other manual solutions for the moment), new android devices are essentially just windows into the lives of users for Google use.
The iOS kernel has been opened for public review in iOS 10, which will help vulnerabilities to be noticed and patched sooner. This brings Apple much more transparency.
Out of the box, iPhones are encrypted, and have excellent baked-in security as detailed at black hat: iphone.appleinsider.com
While android continues to struggle with security due to there being so many different devices, update schedules, carrier update control, and ease of malicious app install.
All of that said: putting in the time and effort to run an android phone without any Google services, F-Droid as your only app store, and your device and storage encrypted can still be considered a better option, but lacks update frequency and ease of use. It is my belief that a phone should solve the problem that you take it out of your pocket for as quickly and effortlessly as possible, while still protecting your security and privacy.
Anyone up for debate? I'm posting from a Galaxy S6 and planning to upgrade to the iPhone 7 this fall.