I know. I would just really love him to do The Joker for an animated version of The Killing Joke.
Honestly... the Killing Joke Joker's probably the only one I don't really see him voicing. It's a very, very human Joker. Those parts with his origin, the way he talks and the way he expresses himself... it's the only Joker story where his plan isn't really to laugh. Hamill's Joker is BRILLIANT, but I don't imagine him being vengeful, maniacal or the usual amazing performer in that story. I imagine him showing Batman something just to make a point.
The only part of the story where I can imagine Hamill's voice, is the singing part, when he says "Don't get eeeeeven! Get maaaaaaad!"
But the rest, even his first laugh, I imagine a more disturbing, screamed and non-funny at all, something another voice would be better at.