Let's start with Google's powerhouse, Android. Android has been picked up by a wide variety of phone and tablet manufactures as their operating system of choice. Android is very popular right now and has a ton of fantastic features. I won't lie when I say that I'm an Android fan. I love the customizability of Android and how if I want different colours, different icons, a different sms application, a new feature, I can simply download an application to make it happen. I've found that time and time again, their are several applications for Android that do the same thing as their Apple counterpart, but at a cheaper price or maybe even free of charge. The fact of the matter is that out of the box, Android allows you to customize a lot more of it's features and appearances. Android gives the user excellent tools for battery, processing and storage space monitoring. I'd also like to note that, being that Android is a Google OS, it works much better with Google functions, like email syncing and calender manipulation. If your not a Google services user then that need not apply. Android has a near endless number of widgets as well. Widgets let you customize the phones home page with applications or almost any content you want, providing you with exactly what you want within just a click or two.
I have to make sure that I mention the big money point, the hardware. iOS runs on it's own hardware, the iPhone (and other non-phone hardware). Android runs on just about every phone, from every manufacturer that will sign the dotted line. You can get Android on a cheap, no camera, no touch screen 7-11 phone for $60 with no contract, or you can go spend $600 on the latest and greatest super-duper phone. Android can be found on a phone that suits your 95 year old grandma or one that can keep up with your 15 year old daughter text messaging 12 friends at the same time. The great thing is that iPhone is (almost) always provided as solid, up to date hardware in a clean package that anyone (seriously!) could use. That being said, your poor Uncle Bob might not be able to afford the $500 iPhone, even with a 6 year contract. It's important to keep in mind that Android is not only successful because they have a great system, but because it is installed on a wide variety of phones, although some drastically better than others.
As a closing thought, you probably didn't learn a whole lot from this. What's important to determine is what kind of phone user you are, how much you have to spend and exactly how much time you have to tinker with buttons and settings. I can tell you one thing, I went Android and I'll never go back!