I could break down the arguments from both sides and see what it comes down to, but that's not what I want to do here. (Maybe some other time.) Both parties obviously have some appeal, and I want to break down what the appeal of both sides is.
iPhone: Consolidation
First of, iPhone scores a big hit with the fact that: 1. A lot of people use it; and 2. All iPhones are made by Apple, so updates come out at the same time. It's also, therefore, easier to integrate an iPhone with a series of external devices because they basically all work the same. Thus the success of Apple Pay and iTunes ride on the back of one set of technology. Security of apps from the app store is better guaranteed (Google doesn't check apps until they're already on the store). Apps admittedly come out quicker for iPhone, and the new language Swift looks like iPhone is going to be easier to program for, as well. (Though Android has the old language beat.)
Android: Choice
I don't know how to put this any better: Android = choice. You can choose from a variety of manufacturers (with good reputations): Samsung, Motorola, LG, HTC, etc., each with its own combination of price, power, storage, camera, customization (I'm looking at you, Moto X), and special set of features to name a few. You can customize literally everything with the right app (rooting may be necessary for some things). You can customize your storage with MicroSD cards. You can choose from more than just iTunes when it comes to even just apps and music. The Amazon App Store works with many Androids besides kindles, and some companies have their own app store, like Samsung. (Note that I favor Google Play for apps.) Heck, you can even use iTunes for your music if you want to! Plus, Google's apps generally have more features on Android (though they're still popular on iPhone). Who favors Apple Maps over Google Maps?
As much as the two systems of iPhone and Android can be seen to be coming closer together, these two differences will always remain. "Why?" you might ask. I'll tell you: Apple. Apple has done something really impressive, actually. They've created a self-supporting ecosystem that runs on a single line of products. In fact, if Apple let other people make iOS devices, people would only buy Apple's. Apple is all about the sleek design and "Everyone uses Apple." And as long as "everyone" uses Apple (There are less Apples than Androids by a HUGE margin, but Apples sell better than any other individual manufacturer by an impressive amount) Apple will always be alive and well, and (unless they misinterpret a new, very important technology really badly,) they will always be able to make new phones (and other products) to satisfy their customers.