Depends on "best".

Singers with amazing range and beautiful voices: Matthew Bellamy and Christina Aguilera.
Singers with interesting voices: Stevie Nicks, Shakira, and Julian Casablancas

Not gonna lie though, when I heard Whitney Houston sing the National Anthem, I got shivers! And, as so many have said before, Freddie Mercury is another one that easily comes to mind. It's hard to choose just one, really.

Ella Fitzgerald, Annie Lennox.
Freddie Mercury, David Bowie.

Whitney and Dido

It all depends on the genre of music. Sometimes even a particular song which makes you nearly gasp with joy at the sound of it. So, indeed, there are no wrong answers, and that is there are so many different kinds of music.

For rock and pop?

Freddy Mercury (gifted beyond belief), Whitney Houston (she elevated the bland pop music she sang to another level) and David Bowie (the man could sing any style brilliantly).

In my book it's Lisa Gerrard. her depth and range are outstanding.In the circles of recording they call her the mic breaker.She also worked with Hanns Zimmer on many movie scores.I don't believe in angels, but if they did exist they would sound like her.

For men I say Freddie Mercury and Luther Vandross.

In the present I think Adele and Carrie Underwood. They don't have to put on a show. They just sing !!

Loreena Mckennitt , Nick Drake both have amazing vocals and are 2 of my favorites..

Without criteria on which to base such judgment answers are merely opinion and sentimental.

There are two different fundamental bases upon which to evaluate best voice that don't even include elements like phrasing and emotional emphasis.

Who can say who is the best? Artists are different in so many ways from one another. Many play an instrument with great virtuosity. I ask do they play the instrument or do they play music? The voice is an instrument through which one can render musical performances. I ask are they using musical compositions to demonstrate instrumental virtuosity or applying virtuosity to a composition in order to render music.

A great voice is one that renders not only well practiced instrumental gymnastics but one that honors composer, piece and audience.

That said, who can compare with Ella?

Lily Pons.

ABBA . Ducks

Joan Collins or Ella Fitzgerald.

Year ago, I went to a Whitney Houston concert. She appeared uncomfortable, stiff and unable to dance. That took the shine off her in my eyes.

I'll say Elvis Presley for a male voice. Or Johnny Mathis, perhaps Nat King Cole....too many.

Whitney isn't a bad choice at all. Although, the best can mean anything.

If we're talking about emotion, I would have to say Donny Hathaway. That guy could make a person believe the world was ending in a few syllables.

Ann Wilson

Yes Whitney no dought at least the ones I heard.

Rob Halford- Judas Priest

Whitney's cousin, Dionne Warwick.

Emmy Lou Harris

Enrico Palazzo

Freddie Mercury or Roy Orbison

Impossible you, I or any of us to determine. I will ask to a professional, a coach with a lifelong experience. In a song, I focus on the lyrics, not the messenger.... the message. Genre bias creates ignorance wedge. So many great voices in so many countries singing styles and languages I never listened to. I am not qualified... how will I know?

Whitney and Steve Perry

Judy Collins.