Nightwish

Nightwish is another one of my favorite metal bands. Soprano singing of Tarja combines really well with metal sound of this band. 

For example, in this song, I Wish I had and Angel. This song is about perfect angle like lover.

Planet Hell instead ramps up the melody to the extremes, showcasing Toumas abilities as composer as together with singing of Tarja and Marko. Here it goes in duet with male metal growl. 

There is also a separate duet of two contrasting voices in Phantom of the Opera. Melody wise, it is more peaceful song, allowing vocalists to showcase their talent.

They have more relaxed songs as well, for example Islander.