Another vote for Geddy Lee - definite top 5 distinctive voice…
Another top 5 DV has to go to Peter Gabriel with his unique “falsetto insertions” (can you think of a better term?) in virtually all of his songs - a trademark voice if you will…
Ozzy is quite distinctive too…I have not heard anyone else duplicate it either. That’s probably why Peter let Ozzy sing “Shock the Monkey” (with Coal Chamber) since he could pull that song off too.
Chicks? Cyndi Lauper…high and squeeky… Enya…very smooth and velvety…
George Thuroughgood is top 10 if not 5…
Roger Waters is quite the screamer/screecher in some of his tunes - not quite singing, but definitely distinctive…