I'm not exactly sure why it's not simply iPhone vs Android. It's not like "HTC" and "Samsung" often have apps that will work on one but not the other. At first I didn't even realize that you did have Android apps, because "Motorola" can be older java-based phones, "Nokia" can be a black and white flip-phone... Not exactly obvious at first glance.

So yeah, just say "iPhone" "iPad" and "Android". Hell, remove the drop-down and make it a logo that you select instead, that should be even easier.