I would vote for Apple as recently I have read about some security issues with android and considering the amount of personal information a smartphone holds and it's importance in your security, it would be wiser to avoid anything that may have some probable security issues. Personally I am a windows phone user (lumia 920) and I am very very happy with it. Very precise and handy but if you are an apps person you must go with iOS or Android as for apps WP is still a huge disappointment
It's all subjective. They all have their strong and weak points. Windows Phone isn't "disappointing" per say as they're the underdog. You can get apps from the native stores or independent app stores such as GiveMeApps, GetJar, Amazon, etc.
We should ask this again by end of this month since the new iphone will be released. Would be nice to see if there is a difference!