Metal fan here, though I am not so big into music that I recognize a lot of whats been mentioned, I'll have to spend some more time and listen to them. Metallica has always been pretty much my favorite band but another I like as much and a lot less mainstream is Iced Earth. They have had problems with the bands members changing quite a bit over time but even with different lead singers and such they still put out some good stuff.
Hard to say what my favorites are, but here are a couple I tend to go to a lot...
That is part of their 'Something Wicked' Saga (
info) which spans multiple albums and songs about how humans were not the first here and they actually came here by force, killing all but ten thousand Setians.
If you go to the actual youtube page, the comments are kinda funny with everyone screaming AaAaAaAaAaAaAaAaAaAa paying homage to the opening scream of the song, which was a good one!
They also have other interesting themes... making songs after historic events, and movies. This song is about the Wolf Man...
I also really like their song about Dark City. I liked the movie too, but honestly like the song better lol.
Their first two albums kind of sucked but after that its pretty good, I think Dystopia is their most popular.