I know i have heared stuff from Amerian Dawn years ago, but the never really got me to listen more often to them. Just like Sirenia, Leaves Eyes, Theater of Tragedy and quite some more bands i checked out in the early 2000s. One band thats quite underrated imho is Edenbridge. Especially the song "Arcana" was very long on my playlist.
oh you like Abba covers? You HAVE to give Feuerschwanz's cover of "Gimme Gimme Gimme" a go. The video is really funny too, but the way they bring folk and metal into the song is simply genius.