There is absolutely no competition IMO between Android and Windows Phone OS. WP wins hands down.
I have used Android before, and believe me, it’s the worst mobile OS I have ever used. Even the unnamed Java-based OSes are much better than "Shame"Droid. Reasons:
Ugly UI which makes me want to vomit.
Too much lag after considerable usage(usually within 2 weeks of buying the Android phone). Even a high-end Android device will lag after a while due to serious flaws in the threading system used in the OS. That’s we we Android haters often call Android as "Lag"Droid.
Android OS is a heavy consumer of battery and other resources. Even if moderately used, the battery life of an Android phone won’t last more than a day. Hence you can see these Android users spending an extra Rs. 1000/- to Rs. 3000/- in buying a power bank to charge their phone at work or during travel.
Not very user-friendly, especially for those who are not tech-savvy and nerdy. Composing a simple text message, making and receiving a phone call and managing contacts are so difficult in Android.
Due to its "open" nature, Android has serious security problems. Android has revolutionised mobile antivirus software because it is the only mobile OS capable of being infected with malware, adware, viruses, trojans and all other malicious software.
Many of the apps in the Google Play store are nothing but malware and useless and sick flashlight and ft and sx apps. Google does not even bother to regulate and monitor the apps being published in the Play store. The quality of the apps are poor and are merely iOS app clones with few aesthetic modifications.
Google owns the online life of the people who use an Android phone. It shoves the usage of its own products down the throats of these Android users and all these products(except YouTube) are sub-standard. It even has the audacity to intercept what the Android users do with their phones. The Android users have absolutely no privacy as a result.
On the other hand, Windows Phone, which I currently use, is the best mobile OS I have ever used because:
Beautiful UI with aesthetically pleasing Live Tiles and fluid animations.
Doesn’t lag much, even on a 512 MB device.
Doesn’t consume much battery and other resources. The battery of a WP device can last 2 days with moderate usage.
Extremely user-friendly. Managing contacts, composing text messages and making and receiving phone calls are straightforward. Senior citizens and those who are not very tech-savvy will enjoy using a WP device.
Highly secure mobile OS thanks to its "closed" nature, no possibility of malicious software entering a WP handset unless infected files are transferred from the PC to the phone.
Microsoft regulates and monitors the apps being published in the WP store. Therefore, the store is free from malware, flashlight, ft, sx and other useless and controversial apps. The quality of the apps are also good and they look unique as compared to their Android and iOS equivalents.
Microsoft does not intercept what a WP user does on his/her phone. And Microsoft products are n times better and user-friendly than their Google equivalents.
The only area where Android is better than WP is in Bluetooth transfer. Bluetooth mechanism in WP sxxxx. WP doesn’t even provide a dedicated folder to store files received through Bluetooth.