I had a look at Asphyre yesterday with a view to using it, but didn't go ahead with it. At this stage I'm leaning towards Irrlicht, or continuing with my own efforts at writing a rendering engine.

I was involved with Powerdraw when it was first released, and contributed a few fixes to it. However I never continued with it. I've always considered the use of components or heavy use of Delphi classes to be overkill and quite inefficient. Maybe that comes from my console development background where you have to be careful about every function call that you make.

edit: Actually, scrap that about Irrlicht. After a longer look at it, I'll keep going on my own rendering engine.