I think that in terms of directors, he was really the breakout talent. Maybe Paul Thomas Anderson would be second, but Pulp Fiction (Along with Goodfellas.) was pretty much THE movie of the 90's! There were a lot of other great movies from that decade, but pretty much all of them were done by old-time directors (Spielberg, Eastwood, Scorsese, etc.).
David Fincher, Spike Jonze, maybe John Singleton? And unfortunately Michael Bay, who may be the most commercially successful of the decade (or the most commercially successful director to come out of the decade at least). Tim Burton made his biggest mark in the '90s but he started in the '80s. Kevin Smith? Not popular enough?