1) HAROMNY KORINE (USA)- Unlike any other director I know working today Korine has something radical new to offer. Werner Herzog said of his shocking debut film, "Gummo": "This represents the future of humanity".
2) HOU HSIAO-HSIEN (TAIWAN) - OK, I haven't seen "The Puppetmaster" or any other of his films made in the 90's, but having seen four of the films he made in the 80's (including the great "The Time to Live and the Time to Die") I must say that he is one of the best directors active today. He is better than Korine, but since this is a list about modern directors I place Korine before Hou because of the radical form and content in his two first films.
3) VICTOR ERICE (SPAIN) - I hope we some day see a fourth film by Erice, because he is without doubt one of the most talented directors ever. 
4) MIKE LEIGH (GREAT BRITAIN) - Is "Naked" the best film of the 90'as? Maybe. Leigh is a challenging and risktaking director, at the height of his powers in the 90's.
5) WERNER HERZOG (GERMANY) - I know that most people think of the 70's and the Neues Kino when they hear the name Werner Herzog. However, I still think that a film like "Lessons of Darkness" (1992) makes him worthy a place in this list. It will be interesting to see his next film, a documentary about the enigma of Loch Ness.
Except Korine there are only "old" men on this list. Hopefully someone will join Korine in his film revolution. "Gummo" could have been the "Breathless" of our time, but unfortunately there are no other young directors nearly as interesting as Korine. 