Interesting to hear all of you... the reason I initially put those four on the table is because of this anecdote from my highschool.
It's about my history teacher, who was considered to be our own Severus Snape (he even looks like Alan Rickman) and always maintained pretty high standards, one day he asked the class, out of nowhere: 'Best movie about Vietnam?'
I raised my hand, all assured, said Apocalypse Now... he says no. My friend raised a hand, said I got it! Platoon, must be, it's Stone! Again, he says no, cold as always.
Finally, I was sure this time, I must've got it - Full Metal Jacket!
Again he says no! I couldn't believe the guy. What's even left? That Robin Williams radio flick (mind you: great movie)?
My history teacher says, like it's total and only truth in the world - Deer Hunter, better watch it kiddos - the bell rang - he leaves the premise, just like that.
Even after watching that movie at least three times until this day I still don't believe him; and I really dig the wedding... and the roulette.