If I did my list in 1988 it'd probably be something like this:
Slayer - South Of Heaven
Iron Maiden - Seventh Son Of A Seventh Son
Metallica - ...And Justice For All
Voivod – Dimension Hatröss
Blind Illusion - The Sane Asylum
Megadeth - So Far, So Good... So What!
Anthrax - State Of Euphoria
However, my actual most listened to album in 88 was Now... 11: I wore out side 4 of the tape with Bomb the Bass, Coldcut, Krush, Jack'n'Chill and Beatmasters featuring the Cookie Crew. I could NEVER let the metallers I hung around with at school know that though.