The amiga versions of games were usually without exception better than ST versions except for ports. I remember seeing chuck rock on the amiga and being amazed at the music and the scrolling backdrops compared to the st version.
But, there were actually a few games on the ST that were better, Robocop 2 was graphically superior and The Addams Family had scrolling backdrops unlike the amiga version. Jim power was identical, something you wouldn't think possible on an ST.
It was really strange seeing these games on the amiga, grab an ST emulator and have a look for yourself.
I personally think that most machines usually have something to contribute. Snes (mario's, zelda, final fantasy, pilot wings), megadrive (sonic's), ST (dungeon master, populous, damocles), amiga (too many to mention), zx81(errr..), spectrum (jet set willy, chuckie egg), c64 (commando, ghost n' goblins), atari 2600 (pacman, centipede), etc
Can you tell I used to have an atari st before I was totally and utterly converted to the amiga?