Here are some post-80s masterpieces:
Mulholland Drive and Inland Empire (David Lynch)
A City of Sadness and The Puppetmaster (Hou Hsiao-hsien)
Grave of the Fireflies and Princess Kaguya (Isao Takahata)
Yi Yi and A Brighter Summer Day (Edward Yang)
Three Colors Trilogy and Dekalog (Krzysztof Kieslowski)
The Travelling Players and Landscape in the Mist (Theo Angelopoulos)
Satantango and Werckmeister Harmonies (Bela Tarr)
Once Upon a Time in America (Sergio Leone)
Distant Voices, Still Lives and The Long Day Closes (Terence Davies)
Princess Mononoke and My Neighbor Totoro (Hayao Miyazaki)
Amadeus (Milos Forman)
Unforgiven (Clint Eastwood)
Life On a String (Chen Kaige)
What Time is it There? ( Tsai Ming-Liang)
Lost in Translation (Sofia Coppola)
Breaking the Waves and Dancer in the Dark (Lars Von Trier)
No Country for Old Men and The Big Lebowski (Coen Brothers)
Wings of Desire (Wim Wenders)
The Fountain (Darren Aronofsky)
Maborosi and After Life (Hirokazu Koreeda)
Distant and Once Upon a Time in Anatolia (Nuri Bilge Ceylan)
The Thin Red Line and Tree of Life (Terence Malick)
Tropical Malady and Uncle Boonmee (Apichatpong Weerasethakul)
Close-Up ( Abbas Kiarostami)
Synechdoche, New York (Charlie Kaufman)
Fucking Åmål (Show Me Love) (Lukas Moodysson)
That's also close to the order I'd recommend them in. If you aren't impressed by any of the top 10 or so then you might as well give up on modern film.