I most enjoy female singers when their voice has some character to it. Ms. Scabbia is certainly very pretty and a talented singer, but to me her voice lacks character...it's a pretty female singing voice mostly interchangable with any other, such as Amy Lee. Anneke, on the other hand, has a lot of character to her voice, even if it isn't as pure or pretty as the aforementioned singers. It doesn't hurt that The Gathering are a tremendously talented bunch of musicians. I think all my favorite female singers have "unusual" voices like that...Anneke, Fiona Apple, Tori Amos, Shannon Harris, Karyn Kuhl, Corin Tucker...
As for the hotness of any given female singer...who really gives a crap if the music isn't worth listening to?