I dunno about that, my favourite demo last year was
Pimp My Spectrum. which didn't have sleek gfx or much of a design but it was still great fun.
I think that the reason there are so few Amiga demos these days is that we discovered beer and girls
Could the problem of lack of gfx be solved with a homage-demo which steals the gfx from much loved Amiga games and then takes the piss with them a bit?
Would be cool, no?
Ever wondered who would win in a fight between the Gladiator from Gods and the Beast? Or if SuperNashwan Power from Xenon II could out perform SWIV? You get the idea.
As for design, I always liked one aspect of ST-Demo's we never really saw on the Amiga. Most Amiga demo's are "film-strip" demos where each scene plays one after another. But some ST-Demos bolted on an interactive "game" as a menu where each "screen" could be selected by entering a room on a platformer, or a building in a 3D landscape etc.