Some of the best metal albums (IMO):
All early Black Sabbath with Ozzy (until Sabotage) - best songs: War Pigs, Paranoid, Fairies wear Boots, Sabbath Bloody Sabbath, Planet Caravan, many more
Ritchie Blackmore's Rainbow (first album with Dio) - best song: Man on the Silver Mountain
Iron Maiden (Number of the Beast and Piece of Mind) - best songs: Number of the Beast, Run to the Hills, The Trooper, Where Eagles Dare, Die with your Boots On, Flight of Icarus
Ozzy Osbourne (Blizzard of Ozz, Diary of a Madman) - best songs: Crazy Train, Suicide Solution, Mr. Crowley, Flying High Again
Motley Crue (Shout at the Devil) - best songs: Looks that Kill, Shout at the Devil
All early Metallica (until ... And Justice for All) - best songs: too many to list
Megadeth (Peace Sells, Rust in Peace, Countdown to Extinction, and the song "Trust" off Cryptic Writings) - best songs: Peace Sells, Holy Wars, Rust in Peace, Symphony of Destruction, Sweating Bullets, Trust
Guns n' Roses (Appetite for Destruction): no bad songs on that album
Alice in Chains (Facelift -- this is metal, the rest of their albums were "grunge") best songs: We Die Young, Man in the Box, Real Thing (pretty much all of them)
Rage Against the Machine (RATM) - best songs: no bad songs on that album
There are many more, of course, but IMO these are the best and most influential albums in the history of metal, more or less in chronological order since Black Sabbath mixed Led Zeppelin with Cream and their own sound and invented the entire genre.