Oh, how could I forget:

Tori Amos
Dionne Warwick
Mahalia Jackson

Those last two directly because of messageboards(Hey ferno). :p

Whitney masterpiece I'm feeling at the moment: God Bless America, live in NYC in 1999. In this patriotic sequel to her legendary SSB performance, Whitney does what she does best: Combines earth-shattering power, clarity, and range, with a torn-from-the-gut gospelicious flair.