"Shout at the Devil" is a good inclusion (and a really good album - so is "Too Fast For Love"), but if you're trying to understand metal that's an interesting detour in that it basically just leads out of metal. Likewise with early Def Leppard or whatever. So many of those bands started out metal and then turned into glam rock, and the trend they kicked off was almost entirely not-metal.

Queensryche is probably a big miss on my part. I barely listened to any kind of prog or power metal after high school so that's a blind spot for me, but you do have to acknowledge their influence. And I do still really like their earliest stuff. So let's toss in "The Warning" (I like their EP better but it's not as polished or representative) and call it a day. "Operation: Mindcrime" was their most high-profile work before they went all pop metal with "Empire," but I'd prefer to recommend earlier and superior material, so "The Warning" it is.

Speaking of pop or rock-based metal, another blind spot for me (intentionally so) is that. But if you want a brief overview, listen to Metallica's black album, "Empire" by Queensryche, and "Wolverine Blues" by Entombed. Three very different takes on what metal bands do with a major label deal and an eye at going a bit more mainstream.

And finally, another significant album I omitted that is worth mentioning is Godflesh's "Streetcleaner." It's an absolute beast, one of my favorites in this whole thread, and was a player in the evolution of metal and industrial (and a lot of bands who straddled the boundary between the two).