Android seems to be selling quite well due to a combination of lower prices and carriers aggressively pushing it over rival models because they resent the control they've ceded to Apple and are able to easily install their bloatware on Android handsets.
Since until very recently 95% of the install base was using a 2-year old version of the OS, we know it's not the killer new features. Since there are no Android-exclusive developers of any importance, the app store is lacking, and Android gets iOS' hand-me-downs a couple years after they've already come out, it can't be the ecosystem. Since mobile traffic from Android devices represents a pittance of the global total relative to their market share, you have to wonder what people use their Android devices for. Are they even using them as smartphones?
Hey, it could be the marketing. After all, who doesn't want a phone that Batman had to kidnap from the back of an armoured truck?
http://www.youtube.com/watch?v=yj9yisLa4ao