What is the best Actionscript3 3D Engine?

Question

I am looking for a somewhat detailed explanation of which 3D Engine for Actionscript3 is the most efficient, practical, scalable, documented, community supported, etc. When

Answer 1

Away3D is the current free champ.

It is in active development, and supports Flash Player 11, Stage3D, etc.

I would also start looking at Blender3D for a game engine in the near future. It's not Flash, but is free, and fairly easy to program. The langage behind it is Python.