Which Vader voice sounded best? (across the entire saga?)

In which film did you like Vader's voice the most?

My favorite will always be ANH. There seemed to be some effect done to JEJ's vocals on A New Hope to make his voice in that film seem less human and more robotic. Am I alone in thinking this, and did they actually do some effect on his voice in ANH?

My least favorite is ROTJ, because even before the Battle with Luke, he sounds much older and more tired. I understand this may have been done intentionally to enhance his characterization in that film as morose and resigned to his fate, but it makes him sound like a tired old man a good chunk of the film. A lot of the menace present in the other films is missing.