ST and Amiga looked like competition to each other because of the wider market they were situated in but they really had different focus and points of success. The ST was a better DTP and general productivity machine and really was a "rock bottom price" competitor to the Macintosh; its gaming capabilities were nothing compared to the Amiga, but I am not sure that's where the Tramiels really wanted to focus anyways.

I never even had a colour monitor for my ST. The paperwhite monochrome screen was to die for back then, and sure beat the interlace hi-rez experience on the Amiga.

And the ST was a few hundred bucks cheaper. Price per mhz, it was a great machine.