To set things into perspective, Mariah Carey may well probably be the best singer since Aretha Franklin.

However, it is widely argued, by professional music knowers, that Whitney Houston is genuinely her equal.

Everyone else is secondary and for me, irrelevant.
These two ladies will forever be THE VOICE in the history of music.

While Carey does not have the other's power,falsetto ,
Houston lacks the other's musicianship,range and the sheer ability to warble.

Equals and forever the best singers of all time or tied in at the 2nd place atleast.