I have been Atari ST owner for many years, i have owned Amiga too. Many people seems to have missunderstand what Atari ST was about.
I have seen so many clips on YouTube or threads in forums where people compare Amiga to Atari ST. Then they say, look, Amiga has better graphics, Amiga has better sound. Those people don't seems to have understand what Atari ST was about.
From the beginning Atari ST was built to battle MAC as a "serious computer", that's why ST used a similar GUI (GEM), so similar that Apple actually sued Atari for using it. ST also used a monochrome monitor for high resolution (no scanlines) and 70 Hz refresh rate that made Atari ST perfect for serious use. Besides that ST contained everything in ROM. Just boot the computer and everything is ready to run.
For gaming ST was considerably more limited then Amiga. While ST just used a simple frame buffer and software generated sprites Amiga contained Jay Miner's custom chips. The only area ST could battle Amiga in gaming was in pure vector games where ST had a bit faster processor, else Amiga was THE computer for gaming.
MAC was the computer for serious use while Amiga was the computer for games, graphics and demos while Atari ST was something in between. The serious computer that could be used for playing games as well. Not to say that demos and games couldn't be good on ST too off course but when Amiga capabilities was used to the full, ST didn't stand a chance.
So, when people just compare the computers for graphics and sound, it isn't a fair comparison because ST was the allround computer made to battle MAC from the beginning.
Many people who bought Atari ST was kind of surprised, including me. Atari was supposed to be about gaming, but not this time. In fact Amiga was way more similar to Atari 8bit then ST ever was thanks to one person, Jay Miner.
This is Atari ST when showing it's real strength. In this comparison, Amiga don't stand a chance.