3D engine or framework for develop ios and android games

Hi,
I use cocos2d-x to develop my 2d games, I think it’s the best framework to make 2d games, but I want to develop games in 3D, what frameworks or engines are recommended for an indie developer?

Unreal is very cool, but hard to learn,
Unity3D may be the best one to indie developers, but it doesn’t open source.
OGRE has its ios port recently.
Cocos3d and Gameplay framework (you can find it in github.com/blackberry/) seems not mature enough.

Thanks for reply,

I already heard a lot about Unity3D, it’s probably the option that I’ll choose(even it’s not open source), I’ll try to use it and see how work.

Cocos3D is availabe olny in cocos2d-iphone(not available to cocos2d-x), and it’s limited to cocos2d-iphone 1.x.
ogre 3d maybe is a good option, I’ll consider if a don’t like Unity3D.

Gameplay is not much popular, I can’t find much documentation about it.