I have two favorites: Rules of the Game, Jean Renoir's sublime and surprising comedy of bad manners; and the sexy, corrosive La Dolce Vita, which rightly made "Felliniesque" part of our cultural lexicon.

Either Delicatessen or Oldboy

Cinema Paradiso is one of my favorites. I'd also include Life is Beautiful, Rashomon, and Babette's Feast.

My favorite foreign film is a mid-sixties French love story, "A Man And A Woman"... I imagine I would still find it a very romantic movie (film). As I recall, it was mostly subtitles but switched to English with French accents... also, switched from color to black and white.
There was a sequel, maybe 5 years later, didn't think was quite as good.

There's a trilogy of French films called Blue, Red, and White. I forget the order you are supposed to watch them. Each very different in style and plot, but ultimately all three are interconnected.

La Vita e Bella

Fantastic Planet.