I had an S4, went back to an iPhone. Got bored, bought a M8 for me and then my misses as she liked it. Now we are back to iPhones.
For me, I loved some of the stuff you can do on Android like dial 532 and it came up with leanness number whereas the iPhone you need to go into contacts or recent. If i've dialled a number before the M8 would remember it and come up as i put it in. These are small things but when you're driving and need to ring someone, that is so much easier.
I take a photo or whatever, i can instantly upload it to photo bucket or whatsapp etc on that screen whereas you can't on the iPhone.
I have a Mac, ipad and now 5S and my employees have iPhones too. I could never get the calendar app to work on the HTC so i couldn't book work in on my phone or see what was on.
For me, iPhones are more restricted and basic (Gally you should love that being a techno t**t) as soon as the iPhone 6 comes out with a bigger screen, ill be buying two of those too.