Its totally personal..
Except this "of all time" list doesn't recognize anyone who was performing before 1955.
That is why it is guranteed fail.
And the type of music is so narrow cast.
Yma Sumac could sing in 8 octaves. Does it make her "better"? I don't know. But people gargling their way through the National Anthem don't impres me-eeeeiiiiiii-eeeeaaauuuhhhhh-eeeeeeeeeeeeeeeeeeeeeeeeee.