For me that's Youthanasia by Megadeth. When I first heard it, I disliked it and thought it had lots of filler. Now having listened to it lots of times since then, I do not really see any weak tracks on the album.
First heard it way back, probably 20 years ago, didn't really click with me. Recently revisited it, instantly tracked down a copy and have been listening to it non-stop. Killer French black metal.