I picked Android, as ever since I swapped from the iPhone to an Android phone I've been able to do so much more with the phone.
iOS had so many little bits that annoyed me - it was pretty much obsolete once I started getting into it forcing me with a very limited app selection unless I wanted to jailbreak which I'd rather not have to do, the apps which I could get were fairly bland and boring, and I had about no options to customize. Combine that with hardware which wasn't all that great, and it became enough of a pain in the ass that I switched back to fliphones until I bought an Android device.
Android is nice as I don't have nearly as many gripes - my hardware doesn't become obsolete in a year and a half due to system updates, I have a massive selection of apps, there's more in-built features which I take advantage of, I can get into the OS and customize to my hearts extent without needing to crack the thing, and apps like emulators (I love my games) aren't instantly removed from the app store for whatever reason. It's been a lot better to me, the hardware which I'm running it on is nicer than the Apple offerings at a lower pricepoint, I have options on who I want to go to for hardware to use it, and it just works.