You're only too right about the State of the Art demo, and that other Spaceballs demo "Nine Fingers" was pretty cool as well.
I used to own an A500 so I'm not too familiar with AGA demos. My favourites were Desert Dream, Burning Spear and Nexus7 for both GFX and Sound.
And, I'm still a sucker for Jesus on E's :-D
I've burned it to CD and every once in a while it still kicks the living sh*t out of my car's subwoofer :lol: