When comparing UDK vs Babylon.js, the Slant community recommends Babylon.js for most people. In the question“What are the best 3D game engines?” Babylon.js is ranked 8th while UDK is ranked 11th. The most important reason people chose Babylon.js is:
Thanks to the increasing popularity of Babylon, it has a growing community of helpful developers. It's easy to find help on their [forum](http://www.html5gamedevs.com/forum/16-babylonjs/).
Ranked in these QuestionsQuestion Ranking
Pro Large toolset
UDK has an extremely large toolset that allows creating almost anything without having to use a 3rd party tool or plugin.
Pro Triple A track record
UDK is an engine used by many big name companies for popular games such as the Gears of War series.
Pro Small (but helpful) community
Thanks to the increasing popularity of Babylon, it has a growing community of helpful developers. It's easy to find help on their forum.
Pro A good amount of easy to understand resources to learn from
Babylon provides a playground where you can explore examples and play with the code.
The official documentation offers a wide variety of well-written tutorials on topics from beginner to advanced.
Additionally, there are many tutorials written by the community available that you can find by doing a google search.
Pro Great base shader material
Pro Actively developed
Babylon has great project health, with activity on Github daily for bug fixes and new features.
Con Superseded by Unreal Engine 4
Con DevKit only runs on Windows
Even though UDK can deploy games to run on multiple platforms, including Mac, it does not feature support for development on Mac.
Con Limits games to FPS
UDK was originally developed for the FPS, "Unreal Tournament", and it certainly shows. While UDK is a very powerful engine, it takes quite a bit of work to make it do something other than an FPS.
Con Young project
Babylon is quite young compared to many of it's competitors (released in 2013). The community is still somewhat small, however growing quickly.