I've gone to an Android set twice and came back to iPhone. Most of it has to do with the fact that my friends and family use iDevices, and I also have an iMac and iPad, so there are more incentives and reasons for me to use an iPhone.
I have to be able to use Facetime with my friends and family. I need to be able to automatically have my notes, pics, reminders, contacts, and stuff like that shared between my devices. I love having iCloud saving. And having universal apps so I can have apps like KOTOR and San Andreas for my tablet and phone, but only pay for it once.
Can't get anything like iTunes U on Android. No app quite as good as iMovie. Apples inertia screen scrolling makes Androids screen scrolling look laggy by comparison.
The biggest dealbreaker for me is Android not allowing you to plug in an instrument. This is because of latency inherit in the OS. With the iPhone and iPad you can plug in a guitar, bass, keyboard, digital piano, or anything with a 1/4" plug, and record, use sound modeling, and effects. I use JamUP so I can have all the standard guitar effects on my otherwise basic and straightforward Fender Blues Junior amp. Having these stompboxes in physical hardware form would cost thousands, and the sound modeling is more than accurate enough for home use, and a bargain. And there's no way in hell I could afford a real Moog synth. My iPhone is an 8 track portastudio, guitar processor, music sketchpad, backing track player, synth emulator, and a music teaching tool that provides me with apps for learning scales, chords, and tablature.
Nothing like GarageBand, Animoog, iKaossilator, Amplitube, Ampkit, or JamUP for Android. Overall the selection for music, art, education is far greater on the App Store. Not to mention games. Why can't SF Volt ever come to Android?
I love the hardware on the top tier Android phones, but my smartphone is 99% a means to access apps and content, so that comes first.