with millions of user having their own likes and dislikes for homescreen and other UI based stuff,
I don't think WP would ever be able to lead on that front anytime soon before they are extinct.
and for a power user who can customize the OS itself I don't think anything other than
Android would be as powerful no matter how expensive WP phone it may be.
So winner is Android, Leave apart the sub-standard low cost phones they do not belong to any categorized users.
Recently I've seen a "Chai Wala" near a hospital continuously surfing and using facebook heavily, while his Tea Boiled and Boiled for his known taste,
I couldn't resist and asked him, are you on android? to my shock (KALLU) replied yes, I had old java phone earlier and facebook was a mess for me.
with Android I work more efficiently, I asked him, to which class you have gone school ? and he laughed out loud and said,
Sir, Aap chai ka maza lo, tayar hai, jaane do yeh sab, mein khush hun is life sey filhaal"
SO those crappy hardware but ability to run newest apps from playstore works very well for even chai wala, why condemn Android, its certainly has reached masses.