Iron Man is the very definition of a badass superhero film. As others have already suggested, it is a movie that revolved elegantly around the protagonist, around the hero, for its entirety. An origin story that made you root for the flawed hero every step of the way, it had action, humor, romance... it succeeded because it literally appealed to every demographic. One hell of a lot of people turned out just to see Robert Downey Jr.'s stellar performance, never mind the awesome special effects and well-crafted story.
The one weakness of Iron Man, for me, was the biggest strength of The Dark Knight - the villain. In most good vs. evil, hero vs. villain type movies, the make or break factor for me is whether or not I find the villain fitting and menacing enough to fuel the plot. In storytelling, it is usually the antagonist who is the driving force behind the tale; pushing it past moments built in merely to flesh out the story and remind us that there is a very real threat that looms at every instant. TDK opted for realism in its portrayal of the hero, but also in the villain, who was crafted not just with an eye to the Joker of the comics, but in an effort to generate what I believe is the archetypal arch villain; literally the best fleshed-out, envisaged, incarnation of a villain
ever to be portrayed on screen.
Obidiah Stane was good for Iron Man, but it's because he is a brillaint and greedy industrialist who wants Tony out of the way so that he can amass even greater wealth and fame. Really, Obi is just there to provide Tony with some opposition as we see Tony's story brought to life. Iron Man is the driving force behind the plot of Iron Man, with Tony's genius literally rebuilding him into a new man throughout the story. Conversely, in TDK the Joker is the obvious "unstoppable force" that moves the story forward at breakneck speed. Unlike Obi, the Joker is very careful to point out that he isn't motivated by money. Why would he be? This is a man who doesn't live by society's conventions; if he wants something, he takes it, he doesn't worry about how he's going to pay for it. Money is useless to him, it's that simple. One villain is the greedy industrialist, the other embraces what it means to be a villain into his very soul. He comes onto the scene in TDK because he
is the bad guy; the message he is endeavoring to send to Gotham, to Batman, and to the world, is that all which separates him from them is that he
knows he's a monster.
Not to take anything from Batman, because in this movie I believe he truly evolved as a character, pushing his boundaries, realizing his limitations, and coming to terms with a new breed of villain which is largely reactionary to his heroic presence. Batman already had his origin, though, in another equally stellar film that I would put on par with IM, Batman Begins. With IM and TDK, one movie is driven by the hero while the other is driven by the villain, and the latter is what makes TDK the darker film. For that reason, I give TDK my personal preference, but it doesn't diminish the brilliance of IM. I just likes me my villains.