Classes in Python or C++ ?

I know how to interface C++ code with python with boost::python and use python in c++ code, but the problem is : How do I make my scripting engine ? I see several solutions : - A class EntityRenderable code in C++ used for representing all contents. And with Python, create classes like Character, Creature, etc. who inherits from EntityRenderable. - In C++ : all base-classes (EntityRenderable, Character, Player, etc...) In Python : use this base-classes for create instances or other classes which inherits from them. - Run the game in Python and use C++ just for graphics, sound, inputs. I have already create classes like GraphicEngine, SoundManager, EventManager, TextureManager, etc. in c++. So, my question is : what is the best solution ? Not only the easier but the solution which permits to have an easily moddable game. Thank you. PS : Sorry for my english...