They all sound great when they're working. It's when they hesitate or stop half way that they cease being musical.
Here, here. But some do have a more distinct sound than others. Weighing in, I would give a nod to either the Hasselblad 553EL/X or an F2 w/MD2 chewing through film whilst set on "M3." Or, for a quieter touch...an M series.
The sound that my cell phone makes when I'm 'sneaking' a Q&D of grandson sounds somewhere between the copal and the compur but not as quiet as my compur electronic shutter. I was not aware that either copal or compur made mechanical shutters small enough to fit in behind that small lens on the back.