the ST sound is chip music based, like SID. Amigas paula can play samples, so it's more sample based music. It depends on preference, some people like chip music ...
but for music production, I think paula is much more useful than a YT. MIDI port is a very cheap and easily obtainable add on for an Amiga.
Falcon is totally another beast, if you talk to Atari folks, you'll see with amusement that they don't even consider it as an ST.
