It's Batman Beyond: Return of the Joker.
But I'm willing to hear arguments to the contrary.
Seriously though, I think ROTJ is like, possibly the best Batman film ever, period. I've always preferred the animated stuff to the live-action.
I also just got done re-watching Under the Red Hood and it's excellent.
I'm gonna be checking out The Dark Knight Returns movie in a week when I also read the comic for the first time.