I'd also put an At the Gates vote in; as well as the Haunted. Sonata Arctica are power metal; but they have a pretty dark sound that I like.
Of course, the kings of melodic death to me are Dissection; they are more black/death but have incredible guitar melodies and leads, with good production and really ferocious drumming, too. Storm of the Lights Bane has to be one of my favorite albums of all time, and the Somberlain is incredible, too.
It's hard to name bands like CoB; they managed to find their own style quite well; but i have heard bands that came out later that sort of try to copy it.