Some favourites of mine -
Mikael Akerfeldt (Opeth)!!!
Simone Simons (Epica)
Fionnuala Sherry (Secret Garden)
Karen Matheson (Solo Artist)
Anders Friden (*old* In Flames)
Phil Collins (Solo Artist) : What... It didn't have to be a metal vocalist list
.
Enya (Solo Artist)
and a few more.
Some I dislike or find annoying -
James LaBrie (Dream Theater) : I don't know, but I personally really dislike his singing.
All rap artists. <-- That's a given.