I'm sure I can think of more but these are my top 3 essentials:
Masquerade - Masquerade (The swedish band) I can listen to this with no skipping, from start to finish
Master of Puppets - Metallica - as much as I hate them now, I cannot deny that this is perfection
Operation: Mindcrime - Queensryche
If I can still add some more, I think I consider these all-killer, no-filler:
You Can't Stop Rock N'Roll - Twisted Sister
Slippery When Wet - Bon Jovi
Stage Dolls - Stage Dolls
I could go on and on...