Had a Galaxy S3 for a year and I hated it. It was just loaded with rubbish I would never ever use and it felt like a cheap plastic toy.
I looked at what I really use my phone for, and I realised that I actually use it to make and receive calls, keeps appointments in my calendar, read emails and message friends. I don't need the massive screen and I really don't miss it.
I have an iPad and a Macbook Pro so everything is available across all devices. No effort and no stress.
I had an android device (HTC desire). I had troubles with the Os, got no update ever, rooted my device and flashed lots of custom roms only to see my battery discharge in a few hours and the camera not working and force closing. thought about buying another android device, but another problem was, that back then (don't know about know) back then there was no way to pay for apps if you didn't have a credit card in austria. switched to the iPhone, got my fathers apps via homesharing and am happy with the device, the support and the OS since then!
I chose the iPhone 5 because, coming from a Blackberry Curve, I found it much easier to use and it looks a hell of a lot nicer and not cheap looking like the Blackberry phones. Surfing on the web is easy, playing games is easy, screen size is perfect for me. I could go on and on, but in all reality, I chose the iPhone because it's something that I knew would work out for me, and by no surprise, it did.