which is best for music Atari or Amiga

[psxphill]

I've also heard about the Atari having very tight MIDI timing, and I've even heard some people complain about Amiga's sloppy MIDI timing.

This doesn't make any sense at a hardware level. The Amiga was multitasking though, so if the software wasn't written well then that could cause problems.
 
There is also http://aminet.net/package/mus/edit/camd which tried to become a standard, but I don't know how good that was.
 
Or you could use a c64
 
http://www.youtube.com/watch?v=BICygZRkKF4

[psxphill]

Yamaha sound chip produce "horrific" sound, but Commodore sound chips are somehow iconic, perfectly silly.

The YM2149 was a slightly updated version f the ay-3-8912
 
http://en.wikipedia.org/wiki/AY-3-8912
 
So it's not really a "Yamaha" sound chip.
 
Back in the 8 bit days it was used on the Sinclair 128 and Amstrad CPC, where it didn't really get the number of people writing decent music to push the chip. I've never heard anything that matches the SID, which was the only really good commodore sound chip. If you have any examples you'd like me to listen to then I'd love to listen.
 
Paula isn't a commodore chip, but we'll go with that if you like. As a sample player it can do anything the YM2149 can do, but with more or less CPU required. Atari-ST demos spent a lot of CPU time trying to make it play samples, but generating samples in realtime on the Amiga would take some cpu time. I think the balance was right though.