^^ I was going to say 'A Simple Plan' too. It's so expertly crafted, the world and characters feel absolutely real. No matter how many times I see it, the death sequences always bring up a palpable sense of dread.
'Cape Fear' (1991) I watched this recently. It's Scorsese's only true attempt at a horror film, and for that fact I love how the majority of it is so blasted with light. You almost get the impression that he thought "you know what? my movies don't have enough sun in them." and got it all out of his system in one go. Deniro and Nolte are in their physical prime. I don't know if Deniro has played as threatening a presence since, save his performance in 'This Boys Life'. It took me awhile to come around to this because it doesn't have the same 'Flash' as Scorsese's other work, and there's a huge lull in the 3rd act before the climax, but with all the shitty remakes we've dealt with since, you have to admit this is a damn good one.
The Fourth Man
Directed by Paul Verhoeven.
This is really out there. I had no idea where it was going when I first saw it and found myself surprised and delighted at that. You can see a lot of the origins for 'Basic Instinct' here, but it's so much weirder. It opened my eyes to how European directors are WAY more willing to explore dark sexual themes, finding true drama and horror in that instead of simply physical violence. I don't even recall much of the plot, so I probably owe myself a refresher, but if you give this a shot you won't be disappointed.