While I prefer the customisable aspect of Android for the user interface, I've found that iOS is working a lot faster and better with applications and utilities.
Android user with an HTC One here. I've had iPhones in the past and I definitely prefer Android. To me, it runs more smoothly and flawlessly than iOS ever did. It's also so much easier to customize!
I am an Android user. And like it in all aspects. Maybe it does not work as fast as iOS, but when being used to something, sometimes it is quite hard to quit.
There is so much you can do when it comes to using Android when it comes to customization and creating new apps. This is not the same to iOS which is kind of complex to use.