I have not seen
A Headbanger's Journey yet, but my friends who did where really impressed.
Most of the bands mentioned on your two lists are there because they were extremely popular at some point or because they were the icons of a genre. Twisted Sister was the undisputed king of metal in 1984 when they released their album
Stay Hungry, but that does not mean they were extremely good (I do listen to
Stay Hungry at times tough). In my teens, I loved a band call Venom (probably the creators of Black Metal), but when I listen to them now, I realize they were mediocre musicians. You have seen it often with movies, it is not because something is popular that it is necessarily good. I am sure we agree on that. If you want to become a heavy metal expert or a heavy metal historian, you have to know all these bands and listen to them, but if you just want to enjoy the music, you don't need to have all of them. Poison's song
Unskinny Bop was extremely popular, but that does not mean it was good! One big problem with heavy metal is that lots of people focus more on the image of the bands than on their music. (That is why many persons don't care about Iron Maiden and why you never hear them on the radio: they don't try to be scary, they don't try to be Don Juans, they just play music.)
It is hard not to mention Black Sabbath since it was the first heavy metal band. They have a greatest hits called
We Sold our Soul for Rock 'n' Roll. I do love the old Alice Cooper a lot, I mentioned
Raise your Fist and Yell because it is by far his heaviest album, but I also listen very often to some of his complilations. Mötley Crüe was a hair metal icon, I have many of their albums, but honestly, I almost never listen to them anymore.
Personally, I avoid Marilyn Manson, Slipknot, Korn, Rage Against the Machine and bands like that like the plague. That does not mean you cannot like them, it is just that I don't like this style of music. Since I don't listen to them it is hard for me to judge them, but IMHO they are just people screaming and jumping on a very basic guitar riff with distortion.
We gave you a long list of suggestions, if I were you, I would go with that and then tell us your preferences so we can give other suggestions when we know the genres you like and the genres you don't like. I don't see the point of having 30 albums of a genre to realize you finally don't like that style.
Please don't see this last commentary as a suggestion not to ask questions anymore. All your questions are welcome, I love sharing my passion and I am pretty sure the others do too. And I am sure we would also all love to have your commentaries on what we recommended. That being said, I do think you are trying to go too fast; take some time to enjoy what you are discovering. I have been listening to heavy metal for over 25 years and I still have plenty to discover. (Like Tarot, Saxon, Angel Dust, Nervermore, etc. In fact, Nervermore is the next thing on my list.)
