Batman Begins is good.
Inception has too many inconsistencies within its logic, great film, but nothing compared to the others.
The Dark Knight is an awesome film, but I rarely felt mentally challenged by it. It was prime entertainment, but nothing else.
I have not seen Insomnia.
Memento is one of the most brilliant movies I've seen, I barely managed to keep the plot organized in my head as the movie went on, but I managed to do it.
However, the vote went to The Prestige, as it's one of the few films that change the second time you see it.
But speaking of Nolan's movies, why the hell has this man not won an Oscar (academy award) yet? He is one of the most impressive directors in the world, he has created some of the most intriguing movies ever made, and those fossils at the academy still haven't recognized him!