I don't know much about windows phones. What do they have going for them?
I pick Android for openness. You can root your phone for more control, and you can do pretty much anything you want with them. You can have a 3d launcher, a 2d launcher with lots of effects or no effects, a minimalistic launcher with no icons completely controlled by gestures, or a complex launcher controlled by swiping your finger from icon to icon. There's no launcher customization on iOS. You can organize things by folder and change your wallpaper. Wow.
Another thing is that you can do so much more with it. With iOS you can't do anything that Apple would look down on. On my Android device, I can plug in my PSP and use it as a controller to play N64 and GBA games from my childhood on emulators. On my iOS device, there are no emulators, there is no plugging in, and there is. no. joy.
Basically, I prefer Android because the list of items that fill the blank in the statement "Hey, I can ___ on my phone" is several times longer than iOS.
Jet fuel can't make dank memes.