The green robot wins on app downloads (but not revenue). As of the past three months, Android is the best place to angle for more app downloads.
According to the App Annie Market Index, Q2 2013 metrics show that Android beats iOS by 10 percent in number of applications downloaded.
However, Apple’s App Store still beat Google Play on one very important metric: the App Store pulled in 2.3 times as much revenue as Google Play.
Android also wins in user interface even IOS 7 cant match up to it. While IOS 7 might look much flashier and nicer, Apple's essentially copying the best of Android and Windows Mobile. Though personally I will stick with IOS.
Note: In terms of popularity with "big company" developers (i.e. Disney , Adult Swim , TBS , Comcast) , iOS , due to its lack of different sizes .
In terms of actual practicality , user friendliness and customization , android , due to its lack of having to be jailbroken for features.
And of course with phone companies , android.