Flexibility and competitivenessAndroid is damn flexible due to its open source nature. Android run on a mobile of price $100 to $1000. Google giant allow manufacturer to customize it according to their requirement and target users. Many manufacturer taste a success with android. Either its world smartphone leader Samsung or developing nation India's Micro-max, Android help everyone. Android is competitive and adapt changes very fast. It launches lots version in less than a decade and continue to do so.
A huge application store Google PlayAndroid is much younger than iOS. still it has big market compare to iPhone. Android users have better choice in application. Most importantly android market contains lots of free application compare to Apple market. It makes users to feel better as they had options. Its free application are not crap, its because it take minimum effort and money to make android application.
A large developer networkAndroid developer network is big because of Google good decision to choose Java as their development platform. Even-though Developer can make their application in native language like C,C++ using NDK in android. Java is consider to be a strong and popular language. It take minimum effort for Java developer to make android applications.
MythI had read some post who are discussing that Android is popular because its cheap. But i strongly disagree with point. Its proven that people does not tend to cheap product until its not prove to be as good as others.
People will doubt Dominoes if they start selling their pizza for few cents.Today many android phone are best selling smartphone which are not cheap. Let Samsung S3 and S4 , they are come into category of cheap. Android is popular because its strong, User friendly and flexible