This is also how I interpret "best." After all, more people may like pepperoni pizza, but if I like mushrooms on mine more, then mushroom pizza is best to me. I love TDK. It's a fantastic movie, and is high on my list of best CBMs. That said, I just get more joy watching The Avengers. It brings me back to my childhood and reminds me why I like superheroes. TDK is amazing art, but when it comes to superheroes, I am drawn to ones that inspire me in some way. The Avengers I find inspirational, so it connects with me more (this is why Captain America, Spider-Man, and Superman tend to be my favorite super heroes). TDK is a wonderful piece of art, but it just doesn't speak to me as much.
But again, this is just me.