Female:
Tough, but I have to go with Whitney Houston. Her anthem from the '91 Superbowl brought tears to my eye the first time I heard it and is one of the best 90 seconds in music history along with the anthem Hendrix performed at Woodstock. She was as gifted a singer as there ever was and I was truly sad when she passed.
Male:
Ronnie Dunn and Don Henley, they defined their genres for over a decade and had songs that touched you on the deepest level. In addition, while he didnt have an "angelic voice" I consider Gary Allsn's voice one of the best in music because of how he conveys his awful life experiences in song.