Did iOS for 2 years. Tried WP8 for a month. Eventually went Android.
If you want a limited, claustrophobic OS, then give WP8 a try. Sure you can resize and color your live tiles incessantly, but outside of that it offers *very* little function.
iOS is very polished, integrated, and easy to use. You aren't going to be tweaking things on end or assigning shortcuts or defaults to a billion different settings. It's slightly less limited in settings than WP8, but it makes up for it in app support and ecosystem integration.
Android is sort of the inverse of either of them. Where they are locked in (keyboards, launchers, tweaks, ect) Android gives you the ability to configure yourself crazy. You can be your own worse enemy there with active wallpapers, high end launchers with hotspot swipes, ect causing lag and crashes. You can also go wild with crazy apps and utils that can access system level files and folders.
Android can be very overwhelming if not dangerous to a person who tinkers without knowing the impact of what they are doing. The apps are typically not as polished and the 3rd party support of accessories and apps and the ecosystem surrounding it isn't as good.
After having Android for a year now, it would be very, very hard for me to go back to iOS or especially WP8. Things like swype, the ability to download virtually any file type, media and folder management and other tweaks and settings are just too handy over the closed system the other two provide.