The Big three are:
Nightwish w/Tarja is completely untouchable. Musically beyond everyone else courtesy of Tuomas and that Viking they thawed out. "Once" is one of my 5 favorite albums of all time
easily. Loved Anette in the band too, proof Tumoas is a musical genius by making music to fit her voice and made it on par with the Tarja material.
Within Temptation - Sharon den Adel is an angel. Depending on the day of the week, she is as enjoyable to listen to as Tarja. Musically I prefer Nightwish - they utilize a wider range of instruments.
Epica - there is not a female lead singer I would rather stare at and listen to all day, than Simone Simons. She has more sex appeal than the entire state of Texas. Most entertaining live too. And on that note, this thread needs a picture of her
I also will mention Xandria, didn't see them mentioned. Their new singer Manuella Kraller is really good. Reminds people of Tarja Turunen actually. New album is fuckin great.
Anette needs love from Nightwish. Imaginaerum was a flawless album. Can easily rival Once, which was the best work while Tarja was with the band.
I would agree with this completely if you listed Dark Passion Play instead. I thought that was the better Anette album, and I wish she was still in the band. People bitched she couldn't sing Tarja's songs, but can you picture Tarja singing "Scaretale" from Imaginarium? She would destroy it.
Of course, Nightwish w/Tarja is completely untouchable and really blows everyone else away. Everyone.