What 3d rendering/ game engine should I use?

I started out (and am currently working on) blender, since it has both a good 3d rendering engine and a good built in game engine. However, I heard that crystal space is fairly powerful and may perhaps be a better choice for a game engine, and ogre may be a better option as far as graphics go. But crystal space is a game engine and ogre is a 3d rendering engine, where blender is both. I know due to an active project (called blender2crystal) that it wont be that hard to export models, animations etc from blender to crystal space if i want, but what I'm wondering is that is it also feasible to make content in ogre and to export it to crystal space? or to the blender game engine since it seems easier to use? Also, I know that ogre has a lot of add-ons such as the bullet physics engine. Would these add-ons serve in lieu of a full-fledged game engine? Or is blender good enough graphics-wise(compared to ogre) and has a powerful enough game engine(compared to crystal space) for me to not bother with crystal space or ogre?