*Thinks a bit*
T-Zero, no question has superlative graphics.
Super Stardust had mouthwateringly good tunnels (better than Microcosm, too).
Darkseed had decent graphics too, but they were in hi-res so ironically made your head hurt, exactly like the game character.
I suppose I have to mention Alien Breed 3D II somewhere here, as well. Nemac iV had excellet explosions, but I didn't like the game at all. Same for Skeleton Krew.
Harlequin had evocative enemy sprites...
Ruff 'n Tumble just looks totally slick. Everything about that game just oozes fun.
Dizzy had eye-catching cartoon ones, too.
For overall beauty, I would choose between Ruff n' Tumble and T-Zero, particularly when there's a lot going on. If you want to check on which games had good graphics (if not the minor issue of any gameplay), look to Amiga Action and see the games which scored more than 90%. 92% for Rise of the Robots? Get outta here...
