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

Papervision3D is going through the process of a full re-write to take advantage of CS4's new 3D capabilities. It sounds like they're also looking into mixing Alchemy into the engine to get a really big boost. You can check it out in a bit more detail here.

I've found that the irc channel for PV3D is fairly active and they've been able to answer any questions that I had due to an outdated tutorial or awkwardly documented section of code.

I don't have the reputation comment yet, so in response to David Hanak's comment above about viewport layers, the best use for them (that I've found) is to help with depth sorting. You can assign objects to a viewport layer and give that layer an index. Then tell the render to sort the viewport layers by index. It really helps reduce visual display errors.