You forgot Pinhead from Clive Barker's "Hellraiser."
But from your list I would pick Hannibal Lecter, with Norman Bates coming in a close second. REAL people who are monsters are a lot more scary than Hollywood mock-up killers. If you saw Leatherface or Freddy or Jason or whoever on the street you'd run in the other direction, but you could be sitting next to Hannibal or Norman in a restaurant and have no idea that they're mad-dog serial murderers.
I like the Wolfman or any werewolf character. My favorite movie featurring a werewolf is An American Werewolf In London. I also like Dracula and Hannibal Lecter but human metamorphasis is one of my favorite Sci-Fi/Horror subjects.