I use Android. I feel that every OS has their purposes.
iOS: Simplistic, very user friendly.
Android: Customizable in every way possible, more freedom to choose from in terms of apps and devices.
Windows: well I dont really know about this. their eco system isn't as well as developed as their competitors in terms of app numbers.
Every OS has their own pro/cons. In my ranking it would be, Android > Windows > iOS simply because there are mroe devicest o choose from and there are bigger screens than the norm 4" and 3.5" that iOS has to offer. iOS is very noob friendly so its nice for people who aren't as tech savvy.