LOTR quite easily. While I consider the final films of both trilogies to be weakest of them all, TDKR just irks me in too many ways. What is it with those 3rd films. It's everywhere.
edit: yeah, about ROTK. I didn't even mind the overly long ending and FEELINGS. It just didn't come together. The battle in TTT felt more epic and intense than in ROTK where it was just...out of focus, boring and lacked all grit. The scale did not transfer to the screen, or to my brain. And Gandalf waiting for his death, but when we next see him he's allright counting the bodies in the wild. Guess that green ghost horde just handled everything in a second. The movie lacked focus.