OK i never owned an Atari ST, always been faithful to the Amiga until 2 years ago that i bought a PC, but as i have used the STEem i can say these:
Nitro is better on the ST
Captive is better on the ST
Tiger Road better on the ST
Operation Stealth better on the ST
Dungeon Master is better on the ST
Super Wonderboy is better on the ST
Pacmania is a crap on the ST
Chuck Rock Amiga crashes Chuck Rock ST
Double Dragon ST sucks
Turiccan 2 ST sucks
Robocop 2 ST sucks
Space Harrier ST sucks
Kick off 2 Amiga is a little better than the ST version
Xenon 2 equal
ST dragon equal
Silkworm + Pang + Populous 1 & 2 + Rainbow islands + Speedball 2 a little better on the Amiga but ST versions are quite good.
Generally Psygnossis games are much better on the Amiga.
Some other games are equal, the most of them is better on the Amiga, especially to the sound.
Thanks i want to see your opinion