Sticking to only one per director, which was hard for Kieslowski and Kiarostami. It's a pretty crap list and i'm sure once i've seen more it'll be altered dramatically.

1. La Belle noiseuse (1991) - Jacques Rivette 
2. The Garden (1990) - Derek Jarman 
3. Beau travail (1999) - Claire Denis 
4. La Double vie de Vronique (1991) - Krysztof Kieslowski 
5. Ta'm e guilass / Taste of Cherry (1997) - Abbas Kiarostami 
6. To Vlemma tou Odyssea / Ulysses Gaze (1995) - Theo Angelopoulos 
7. Viagem ao Princpio do Mundo / Voyage to the Beginning of the World (1997) - Manoel de Oliveira 
8. Tulitikkutehtaan tytt / The Match Factory Girl (1990) - Aki Kaurismaki 
9. Le Tombeau d'Alexandre / The Last Bolshevik (1992) - Chris Marker 
10. Lektionen in Finsternis / Lessons of Darkness (1992) - Werner Herzog 

It was hard to leave out Crash (Cronenberg), Lost Highway (Lynch), Dead Man (Jarmusch), Festen (Vinterberg), Henry Fool or Flirt (Hartley), Underground (Kusturica), The Thin Red Line (Malick), Safe (Haynes), Short Cuts (Altman), Cremaster 2 (Barney) and Days of Being Wild (Wong) and many more i've probably forgotten to mention.

I haven't seen anything by Tarr, Hou, Tsai, Kore-eda or Godard from the 90s yet. Aside from a whole host of others.