Hi, Unity3D is great. But we are cryengine.com which is very good. Do not forget the Unreal.
IN fact, it all depends on what kind of game you want to do. If you're an adventure game or FPS, for example. It is also important to know if you develop a 2D or 3D game.
Ideally a little research on each engine. And something that is good to point out how much you want to provide time to learn and, and make the game. Lenve in consideration that one day you may need to serve many users. Then comes performance, and in this case recomento C ++ and OpenGL.
Please search for long before you start.
I am available,
Alexandre Luís Rigotti