Most Influential Extreme Metal Albums
It started a new genre
First death metal album.
This has my vote.
Not the best Metallica album (still great though) but I think it was their most influential album because it started thrash popularization.
Cambio la musica para siempre
Influenced Megadeth's Rust in Peace and their next recordings - as a result Megadeth stuff became even more technical, especially guitar work. Alice In Hell and Jeff Waters impressed Dave Mustaine - I guess it's not easy to impress him with guitar skills but Jeff Waters did.
For Rust in Peace Mustaine wanted somebody like Jeff Waters on the lead guitar and because Jeff declined to join Megadeth, Dave hired Marty. And Marty was an incredible technical guitarist, too.
Actually not only Megadeth but also the stuff of the other thrash bands became more sophisticated in the early 90s thanks to Alice in Hell. Competition works, haha.
Some proof that it influenced Mustaine? Some evidence to back those assertions?