Amiga never had 24bit sound, but what people did with its 8bit sound is amazing and should never be forgotten.
Well, the Repulse audio card for the Amiga gave it 24-bit audio. But not much took advantage of this (SoundFX maybe). OctaMED SS could render to 16-bit wav files. But as you probably meant, most Amiga music was made with the 8-bit Paula audio.
Anyway, 16-bit and 24 bit audio is a bit over-rated - especially for electronic / chip type music. It's not how many bits you have, it's how well the music is written. So I agree with you, there was some great 8-bit Amiga music. I was never really into MODs, but some of the ones that stick out are the music from Alternate Reality, The Pawn and Hybris.