She would also have been among my top three choices. Definitely one of the most powerful female voices in metal. The other two of my top three aren't listed in this poll either, namely former Atrox-vocalist Monika Edvardsen (one of the most original vocalists) and former Détente/Fear Of God-vocalist Dawn Crosby (R.I.P.). Since none of these three are mentioned in this poll, I voted for Anneke van Giersbergen.
As far as non-metal is concerned, my favourite vocalists are Kari Bremnes, Kate Bush, Mari Boine, Lisa Gerrard (though I'm not too fond of her recent solo stuff) and Sainkho Namtchylak (the latter having probably the biggest vocal range of them all).
Unlike most people here, I generally prefer female vocals to male vocals.
She sang on Lovelorn like she had been caged up for years and, in a sense, she was with Theatre of Tragedy switching to electro-pop music. Great album.