I'm a vocals slut. I like a bit of everything..
My all time favourite vocalist is Silvio Massaro (Vanishing Point, Manic Opera). Vanishing Point are his main band. They're a Power-flavoured Melodic Prog Metal group from Australia. In terms of powerey vocals also love Jorn Lande's voice (Jorn, Masterplan, Ark), that of Time Grose (Dungeon, LORD) and the great Ronnie James Dio (Rainbow, Dio, some Black Sabbath) and Bruce Dickinson (Samson, Iron Maiden). Devin Townsend is another favoutire (Strapping Young Lad, Devin Townsend, Punky Bruster, Steve Vai's 'Sex & Religion'), Zakk Wylde's voice matches perfectly with his guitar wanking, Michael Akerfeldt (Opeth, Bloodbath's 'Resurrection Through Carnage) has great death vocals, Pepper Keenan (Corrosion Of Conformity) has a sweet voice too, Clint Boge (The Butterfly Effect) has one of the best and most unique voices in Australia, Altti Vetelainen (Eternal Tears Of Sorrow, Kalmah, For My Pain) has a good set of lungs too, one that matches very well with the very-Melodic Death Metal he's been involved with. Cucky Billy (Testament) owned arse on 'The Gathering', Chris Hall (Stabbing Westward, The Dreaming) also has a strong set of pipes too.
...if I go on, i think I'm going to be here for a few hours so I'll leave it at that.