Can you clarify the question
If you can tell us what you're a looking to do with the device we could then offer our opinions. I was an old iPhone user myself until I recently went to android.
The iPhone has a very good interface and the apps are all QA'd through their online store. One of the major annoyances for me with the iPhone was you don't have a directory structure on the phone you can access. For example I have an FTP client app on the iPhone, I use that to connect up to either my own (or someone else) FTP site and download something. In most cases I can't then go to another app to actually use that file, as each app is isolated and you are prevent from accessing that location (there are a couple of exceptions to this but not many).
The android by comparison isn't as well polished on the user interface side of things, though it has really improved over the last couple of years (which is one reason I made the switch). Google have also released "google play" which is their app store, unlike apples app store none of the apps to the best of my knowledge are QA'd by anyone else other than the apps developer. With an android you get a file explorer app (much like windows explorer), so when I download something to the device I can then easily use another app to navigate to the relevant folder or open it directly via the file explorer app by picking the application I want to run it with. There's a lot more freedom on android and though there have been one or two things I missed on the iPhone, it has been more than made up for by the things I can now do with an open eco system on the device. Another plus is the Android phones tend to come with bigger screens, compared to the iPhone 5 and I believe apple devices still do not allow you to install flash players on them.
It really comes down to what do you want the phone to do, if it's just to do really boring stuff like make calls, take pictures and text message then either device should be up to the task, apple might currently be the better choice as it's UI is still more polished than the android OS. If your picking a smartphone because you actually want to use it properly and make the most of it, my recommendation would be to go for android.
Android for me - especially if you can get your hands on the Nexus 4 - £250 sim-free for the specs is a bargain. Agreed the iOs is slicker, but I'm averse to paying a premium for the brand. Love the fact that with my phone and tablet, I can personalise the look as well.
Personally I would opt for android. Why... for a start it's a more open platform, you can install apps from the internet should you wish (your not tied to the app-store), the 'google voice' app is quicker and more accurate than 'siri'. Google maps and google nvigation are both free accurate and work well. Android is more customizable the iOS... All this said it is really down to user preference. Its best to go and try both out and see which YOU preffer.