The decision to leave your iPhone and join the world of Android is not easy. For many people, it may not even be the right thing to do. I think it all boils down to three questions you can ask yourself. By answering these you should know the truth about which ecosystem you'll be happiest in.
1) Do you want to customise your user interface?
The easiest difference between Android and iOS to notice is that Android allows a ton more options to customize the user interface. This goes further than just icons and widgets however. Android opens up the opportunity to replace your keyboard, replace stock apps, and of course use widgets to view app content, change settings, amongst other things. Take a look at some creative home screen customizations below, and decide if this would appeal to your tastes. I took these from the last few days in the Android Themes community on Google+, but the creative options are virtually endless.
2) Do you use Google often?
Do you use Google Now? Calendar? Gmail? Google services are born and bred on Android, and while on rare occasion the iOS experience is stylistically better, the Android version is typically a step ahead and a step more functional. A lot is said in the tech community about Google getting better at what Apple is good at, faster than Apple is getting better at what Google is good at. The meaning of this statement is ultimately that today an Android phone isn't far off the "perfection" of the iPhone, but the cloud services Google supports it with are stronger. If you use Google's services more than the competition, Android will bode well for you.
3) How much do you love mobile games?
This is a question to swing you back in the opposite direction, and I feel it's important. While the tides may slowly shift as Google improves its strengths here too, today games are still better on iOS. They tend to launch first on iOS (think Temple Run, amongst many others) if they launch on Android at all (think Kingdom Rush - my favourite mobile game, only available on iOS). The only exception to this seems to be Angry Birds, which is generally cheaper on Android (at one point a version of Angry Birds was free, but $4.99 on iOS. I forget which and when.) For the time being if you think of your device as a gaming device before all else, you might stick with iOS for the time being. That said, I love playing mobile games, and waiting a little longer for major titles hasn't bothered me much. There is a large app store full of indie games waiting to be discovered on Android, as well the opportunity to install an emulator, so you can replay those classics!