For 3 different bands, that sound so different, but offer something collectively so influential and genre breaking in the space of a year, 1986-1987 remains one of the best musical memories for me.
Reign In Blood (Slayer) is the best in my opinion, but Master of Puppets (Metallica) and Among The Living (Anthrax) are very close. These records along with the rise of Public Enemy and initial success of the Beastie Boys, such a melting pot of creativity then. Lit things up.