Me being an opera nut, I'll start off with my favorite opera singers:
1. Leonard Warren- An incredibly huge voice with exceptional lyricism, this man for me defines the "Metropolitan Opera" sound. And his interpretation of the title role in Verdi's Rigoletto is without peer
2. Jussi Bjoerling- Perhaps one of the most beautiful tenor voices to ever grace the opera world, Bjoerling had a smaller instrument compared to some of his contemporaries, but his intensity and sheer passion shone through every time. Listen to him singing O Holy Night in Swedish and you'll see what I mean.
3. Diana Damrau- A beautiful woman in possession of a beautiful coloratura soprano voice. Her signature role for me is the Queen of the Night from Mozart's The Magic Flute. Not only does she make one of the most difficult arias in all of opera look easy, her acting was the icing on the cake. She was fierce, ruthless, and had murder on her mind, just like the Queen herself
There are many more opera singers who I love, but this list would never end, so onto the rock singers!!:
1. Dio. Need I say anything more?
2. Myles Kennedy of Alter Bridge- Arguably one of the best vocalists in rock today, Myles combines an incredibly high range and perfect vocal control with incredible emotion put into every syllable
3. Serj Tankian- His work with SOAD as well of his solo work shows an excellent understanding and control of the voice, with all the sounds he makes in his music, with a gift for singing softly with intensity.
Again, there are many more I could list here, but I don't want this post to be any longer than it already is.