Mmmmmmmeh, I'm going to call BS on Fury Road being the best Mad Max film. It was cool but it was also silly and I can't remember anything about the plot after seeing it.
Mad Max: The Road Warrior is easily the best of the films. Gritty but with a bigger budget. There was a story that took place in a world that made sense. There were 4 factions at work: Max, the Pilot, Lord Humongous with his gang and the Villagers. They all have goals and a place in the world. The vehicles were cool but still looked like they could actually exist and work in that world.
Fury Road wasn't bad, it's just not the best.