Vertigo. Saw this soon after it came out, but being 11 at the time I couldn't make much of it. It's aged pretty well, considering.
DEfinitely, I'd argue that most of those Hitchcock classics have aged well. Rope is another good one.
Watched Birdman last night, I can see exactly why it had the oscar nominations, and can't think of a better film I've seen recently.
For all the hype over 1917, I though the plot fairly dull and couldn't really relate to the two characters, in that respect it was much like one of the old Fighting Fantasy books - which choice will you make, shell hole to the left, or the dark forbidding tunnel? It was only really the cinematography that saved it for me. Maybe we've all just had too much of the upping of the horrors of war from Saving Pvt Ryan, to Hacksaw Ridge and now this.
Birdman by contrast was far more engaging, far more depth of character and more to empathise with and get your teeth into.