Both the operating systems are decent and they both have reasons to be bought (especially since there's some specific apps developed for one or the other), but I still much prefer Android with the ability to simply plug it into a Windows or OSX or Linux PC and just directly browse the files on my device. Plus there's tons of custom ROMs that are easy to install and use as well.
Now, in terms of hardware, it's a massive and clear loss on Apple's part, what they charge vs the hardware you get is insane. You can usually pay 200-300$ less and get and Android phone with specs that are as good if not better than whatever the latest iPhone is.
Plus, as a final note, Nouget is out (Android 7) and it has some AMAZING kick ass features.
tl;dr: Android