Android is making the same mistakes as Windows Mobile — unsigned apps, no sandbox, poor dev tools, and cheap phones...’

Which mobile OS ecosystem is best for enterprises?
Windows Phone 8 has many advantages over all others, which
I quickly list below: 1. Tight integration into most "enterprise"
software - Active Directory, Exchange, SharePoint, Navision, etc.
2. Full fledged and most comprehensive Office package for any phone OS. Native Word, Excel, PowerPoint, OneNote.
3. Ability for IT managers to set policies that apply on the
phones as well.
4. Secure enterprise marketplace for each organization.
5. A "My Company Hub" - a unique experience that allows interacting with organization data and apps.
6. Tight integration with desktop/laptop software - Windows 8, Office, etc.
7. Cloud connectivity allows easy roaming.
8. Best in class application development - great tools, easily available developers on .NET - can allow creating company specific apps and distributing them within the organization very quickly.
9. Win Phone 8 apps : Ability to create apps that target both  desktop/laptop and mobile platforms - tablet/ phone - very, very easily.

Which mobile OS ecosystem is best for consumers?
In this case, the choice would be between Apple iPhone and Windows Phone. Both stand out for the following:
1. Well integrated, secure ecosystem. Chances of malware is minimal. Android is extremely susceptible - not at all recommended.
2. Investment into the platform can pay off quite well - using Apple iTunes or Windows Phone Xbox+. Android/BB has no such ecosystem.
3. Good control by the original companies (Apple/ Microsoft) on what you actually get. Why Windows Phone beats iPhone in this:
1. Design is much more sophisticated AND functional than the iOS one. Read: http://on.wsj.com/WW4WRh
2. The Xbox+ services beat the iTunes stack. Music, Videos, etc. are common, but you also get Games (Win8, WP8, Xbox), cloud and more.
3. Number of Microsoft controlled devices for all budgets. From 9K to 35k+, Nokia, Samsung and HTC phones. Apple has one current phone at any time. (Note: Unlike the Android cheap phones, these phones have to be actually approved by Microsoft for giving a suitable UX.)

Which mobile OS ecosystem is best for Developers?
In terms of pure development - nothing beats Windows Phone. Just compare the tools (VS 2012, Blend), languages (C#, VB, XAML) to the other choices (Apple: Xcode, C++; Android: nothing, Java). However, in terms of market, I would go with Apple and Windows Phone. Apple has a massive base that cannot be ignored.

Windows Phone has the highest year-on-year growth as compared to iOs and Android. In Europe, both iOS and Android have declined in the last qtr with WP actually taking up that slack! While I know Android is growing significantly, I would consider it as a bubble that will soon burst. It's
following the same pattern as that of Windows Mobile - which grew rapidly from v3 - v5. And after that simply collapsed. If you notice, Android is making the very same mistakes - unsigned apps, full fledged APIs, full access to phone resources, no sandbox, poor dev tools, cheap
phones that spoil the actual experience, fragmentation by OEMs and more.