Agreed on Bundy, although I'd also include Dahmer in the list of people who had few to no redeeming characteristics. There was really nothing in his upbringing that gave him any excuse for what he did later in life. Richard Ramirez has something of the woobie to him, as he went through some genuinely heinous stuff as a child, including his insane uncle murdering a woman right in front of him. However, rather like Bundy and Dahmer, he reveled in his own acts of violence and the subsequent attention it got him. So he's really pretty unforgivable himself.
I can't really think of a single serial killer who one would be justified in saying found any kind of redemption. As Bob Keppel said about Ted Bundy after interviewing him for an extended period of time, these people basically have a black hole where a normal person has a personality. Nothing could ever fill that kind of void. Someone like Bundy would kill the entire human race and still be unsatisfied.