Requiem For A Dream (Aronofsky- Intense. Be ready for quite a trip
Casino (Scorsese) - Classic Scorsese. Great soundtrack, story, and technique.
High Plains Drifter (Eastwood) I don't know.
All great films. I prefer Goodfellas to Casino but there both still brilliant. Also there are other Clint westerns I like better the High Plains Drifter but there all good.