Oh yeah, the big Mommy of metal around. Nightwish is probably making to most money out of other (metal) band by female singer. Tarja was a big force before and now Annette is doing, perhaps, equally the same now. What I like is the song writing of the band is highly original. All songs are highly memorable and with good melody composed to stand the test of time.
2. Within Temptation
WT is going the same way of success along Nightwish although their music completely different. The last albums of Within Temptation, the Unforgiven (2011) is something very powerful in song writing, although metal fans will complaint of their less heavy tunes. Compare to Silent Force era of course. The singer is Sharon den Adel, probably my most favorite singer with clear voice.
And yet again a completely different band to the previous two. Fairyland is from France and they are playing even more serious music than Nightwish and WT, that is the Symphonic Metal genre... \m/ Their three albums are great, plays Symphonic Metal alike of Rhapsody of Fire. Fairyland female vocal sings by Elisa Martin, Flora Spinelli and others. Sadly, Fairyland is not a stable band with only one composer and founder of the band left as per 2011.
And now, Epica is the first true Gothic Metal over here that stands out from their contemporaries. Singer Simone Simons is the soul of their vocal line.
Very much the same league with Epica, with more unisonic vocal line and thick string over the song.
6. After Forever
After Forever is a bit heavier than Epica and Sirenia, and the singer uses sopranoic voices instead the soft whisperic voice. Music are a bit progressive. Unfortunately, After Forever disbanded in 2009, singer Floor Janses is now in the band ReVamp.
Edenbridge plays standard symphonic metal tune. With singer Sabine Edelsbacher, Edenbridge is what the double pedal drum and guitar riffing should, and always, sound in female variant.
8. Visions of Atlantis
Visions of Atlantis is a duet female and male vocal symphonic metal band.
9. Leaves's Eyes
A less known, maybe the band names is a bit less metallic, but the band is no less catchy. Singer is Liv Kristine.
10. Arch Enemy
Oh wait, kids, Arch Enemy is a female front metal band for decades now, but they are not the symphonic / gothic type. Obviously everybody know A.E. is Death metaller, the melodic death metaller though, as per metal storm classification.
and others worth mentioned here:
11. Seven Kingdoms
13. Amberian Dawn