I love Chante Moore, Erykah Badu, Amel Larrieux & Lauryn Hill. Diana Krall & Sarah Mclachlan blow me away with their talents and strong lyrics. Finally, if you have not heard of Lala Hathaway and you love a deep jazzy vocal - put it in your ear; you will most definitely be pleased.
Back in the late 70s - early 80s, it was definitely Debbie Harry! I loved the way she combined great music with great fashion and style! Also Madonna for similar reasons. On a purely music level, it was Emmylou Harris.