Moai SDK vs Felgo (formerly V-Play)

Because it uses Lua + C++.

You can use your own custom shaders and extend the language with C++. MOAI doesn't give you everything, instead it gives you the tools you need to develop any game you want.

So it is extendable with C++

Uses a limited subset of Lua

Moai SDK is used by popular developers including Double Fine for their mobile game, Middle Manager of Justice, and for their Kickstarter hit, Broken Age(formerly, Double Fine Adventure.) It was also used to create the popular mobile game Bubble Ball 2.
This proves that this engine can be used to make fully-featured and fun games.

Has options for development like Hanappe and Rapanui, providing a different way to interact with the engine.

The Moai SDK Forum is active and users will go to great extents to answer queries, post code snippets, beta test, and even purchase and give feedback on each others' games.

Although the Moai SDK is very advanced and uses complicated features, the documentation wiki thoroughly and clearly explains how to use these features, such as the Moai Cloud(a service that provides web services for your game), and multiple ways to build from source.

Qt-Creator IDE with Code Completion, Debugging and Profiling, integrated Quick Help, Version Control and more.

Felgo is among the easiest cross-platform tools to use according to a survey done by research2guidance.

With the Level Editor components, you can let your players share their levels with the whole game community which is cool because you don't need to create new levels on your own, but the community helps you with it. There are other community features like rewards for good level creators that helps getting more downloads.

Leaderboards, Achievements, Challenges are available across platform, even on Desktop. You can also use Cloud Syncinc of your game data that makes it easy to start a game for example on iPhone and then continue on a Nexus Tablet or the other way around.

It is also convenient because sharing to all kind of game services & networks like Facebook & Game Center is possible with a single API call. Custom hosting of Game Network servers is also possible if you want to keep the player data.

Although game logic is provided in JavaScript by you, performance-critical parts of the engine like OpenGL ES rendering or particle effects are implemented in rock-solid C++, providing the ultimate performance your game deserves.

Advanced Gaming Components for handling multiple display resolutions & aspect ratios, animations, particles, physics, multi-touch, gestures, path finding and more.

No need for native SDKs, Build in and Install from Cloud with the Felgo Build Server.

Cut your development time in half. Using the QML language allows for some powerful features that cut code lines and time. Another helpful feature that can help in this area is that there are more than 50 game demos of all genres that come with full source code, meaning one can easily check to see how something was done.

Felgo has friendly forums where core developers participate as well as fast & helpful email support.

The Qt framework is a great and mature framework on its own. Using Qt as a game engine base is a smart idea.

You can use ready-made components to balance any of your game properties at runtime, so also on mobile devices which is great for adjusting forces or input parameters.

Helps get started and improve with lots of tutorials, demo games, examples.

In-app purchases, game and social network integration (such as Game Center and Facebook), ads (with Chartboost and AdMob) and analytics (such as Flurry) are all available across platforms.

Every 2-4 weeks new updates provide additional features and fixes based on what users wanted the most.

You can even monetize these user-generated levels with in-app purchases with the Felgo Level Store component if you like.