Amy Lee (Evanescence)- absolutely love her. Her music opened doors for me as a kid
Meat Loaf- he's got a gorgeous voice. He can literally sing about a box of cracker jacks and sell it like a five star classic.
Sharon den Adel (Within Temptation)- fantastic soprano voice.
Tori Amos- her voice isn't exactly powerful or polished, but it is raw and real and you can hear it in her lyrics. She writes about a wide range of topics, all with a kind of honesty and quirkiness that only she can deliver.
Trey Anastasio (Phish)- Trey just seems like the sweet, eccentric, and down to earth dad with the giant cd collection in the living room that every kid dreams of having. The bands lyrics are silly and make no sense most of the time, but they can get pretty real too. I'm not gonna lie, their song "Joy" gave me the feels.
Kurt Cobain (Nirvana)- Gawd, I feel for Kurt. As a musician, he's an exhibit A example of how an artist doesn't have to know what they're doing to be successful-- and sometimes, it's that uncertainty and rawness that really makes their work so powerful. As a person, he's someone that you miss even if you've never met him. In a world of stars that are so machiavellian and capitalistic, Kurt's reluctance to rise to fame and his consistent punk-rock, pro-feminist, pro-civil rights values were refreshing.
Holly Brewer (HUMANWINE)- not very well known, but she has the most gorgeous voice I have ever heard. She's been through so much as well.
Bradley Nowell (Sublime)- I love his voice. Personally, I always favored Sublime's more melodic songs over the faster punky-er ones because those were the ones that really showcased his talents and set the band apart from other punk groups.
Others are Kesha, Nina Hagen, Liv Kristine, and Cat Stevens