I agree with your post mostly, but what exactly constitutes a "power user"?
Well, we could argue about that all day, but I argue that it doesn't really matter: no matter what it means, they're more likely to use Android. If it just means they are going to want to use a broad variety of apps from disparate sources, that's Android. If it means they want to customize their phone as much as possible, even just bling-bling style, that's Android. If it means they want to tinker with the internals, obviously that is Android. If they care about security and controlling what apps can do on their phone, that's also Android, albeit one of the cooked-down versions and without Google services — but you can do that if you want to.
You could argue that any of these desires makes you a "power user", but clearly any of them will also lead you to Android. If you took some of them to extremes you might end up someplace else, but it wouldn't be iOS or Windows Phone.