For now, choosing by your needs. What do you need exactly? A phone for gaming or a phone to keep up to date? A phone for lifestyle only or the phone for work around?
Android phone have many possibilities to do something like gaming and lifestyle, also updating your status on social media. It have million apps to use. So you can choose whatever you want to use. Android allow you to customize your phone because the root feature on Android system. It can share some apps by sharing apk files. Its open source after all.
Meanwhile in Windows Phone, you can do all that stuff but only with a fewer apps. But the windows ecosystem let you using the cloud service that very amazing to me. Yes Google can do it also, but because Android OS only available in phone right now, so it less important if you compare it with one drive and Office 365 that can run in any OS and any PC. It just like PC in your pocket. Well, WP for me is match with working and students people who need some phone "To Do" something, or produce something. Like the ad, "For People Who Do".
So, for me Android is for someone who need to playing around (thats why they called it Google Play). And WP is for someone to do more than just play. With the coming of Windows 10 mobile, I wish the app gap issue will be no more.
I let you decide about which better UI and UX on each platform. Its relevant for everyone I guess. Android have widgets and WP have live tiles. I hate arguing about which better.
So, if you have any question just ask here.