The shadows of acdfsm are great but the level is weak.
The seavtf looks a bit strange to me. Maybe the shaders are just exaggerated.
ShadeC is very promising but the indoor shadows are too blocky.
Shadershowcase is nice but needs better artwork and shadows.
The tower (on planet) is impressive but I dont know a good application in a real product for this.
Wavefield looks great. Only the harsh lod of the water destroys the illusion.
I was surprised by rayharilightsoft. It is very well made and offers lots of features I did not see in Gamestudio so far. Very well done Julz! You got my vote. I really did not understand why you dont have more of them.

Many demos have problems when I switch resolution (F5) or when I switch to full-screen. And most of them dont offer wide-screen resolutions. This is annoying and not applicable to real projects.
Sometimes I realized another strange effect: Demos like the wavefield run very fast in a window but are slow in full screen mode.