As I stated earlier, it would be meaningless to announce the winner, but I do wish to express my preference. Developer of both OS have huge amount of experience, knowledge and fame. For me, the best educational tool would be Android. Being able to develop it in your own needs (Open Source Code) is the initial reason why it should be used. You may restrict or give full permission to your students to operate their mobile learning assistant. Another significant reason is Affordability. With the money spent on the cheapest iPad, you may buy a few (minimum 3) Android tablets running on latest OS, and with a dual core processor. It depends on the country you live in, here in Turkey you may buy one iPad mini (wifi) or five Android tablets. If we are talking about mobility or mobile learning it is not only about Tablets but Smart Phones as well. The same rate (almost) applies to phones. I hear some people say, but “they are not the same quality or functionality, apples and oranges idiot!” I just want to remind “educational use”. Number of general and educational applications are really not a matter of concern. Numbers are increasing but Apple is for sure way better in this business but my personal opinion is that there are more educational apps because payment either through app sales or ads are better than Android. Also sales channel of Apple is better as it is a cool and maybe prestigious device to have. I want to share my experience; I needed to borrow an Android device in the UK but I just could not, as all operators raced to offer the latest Apple product on really fair rates on contract. Whereas in developing countries people still want to have a Smart Phone with an affordable price. The last and the most important feature is File Sharing. I hate receiving or sending files or pictures to/from my iPhone. All the features that makes it super safe also makes it boring. Bluetooth connection attempts failed both in Mac and PC. You have to install applications or everything has to go through iTunes. As teachers we have a lot of audio files, videos, documents in various formats, pictures etc… With Android it is really easy to share files, devices have extension slots and by SD cards you may swap files from computers or devices. Bluetooth becomes life saver when you don’t have cables or memory cards.
Educational Apps in App Store: http://www.statista.com/statistics/166976/popular-categories-in-the-app-store/
You will find more statistics at Statista
You will find more statistics at Statista
Number of Apps in iOS and Android: http://www.statista.com/statistics/208599/number-of-apps-available-in-leading-app-stores/
You will find more statistics at Statista
App Store Stats: http://148apps.biz/app-store-metrics/
Comparison Numbers (Developers): http://www.androidauthority.com/google-play-vs-apple-app-store-2012-76566/
Top Android Categories: http://www.appbrain.com/stats/android-market-app-categories
More on Android App Numbers: http://www.businessweek.com/news/2012-10-29/google-says-700-000-applications-available-for-android-devices
emrah akkurt 
Long live Android!:)