Nephthys
The Gr8est!!!!!!!!
All of this, though, is subjective. How do you determine a strong personality? I would argue that Palpatine has a strong personality; you'd be inclined to disagree.
Which is why we are discussing it through the use of evidence. If you can bring forth proof that Palpatine isn't just the cackling stock villain which I believe him to be then I will gladly conceed that he has an actual personality to him rather than UNLIMITED POWAAAAH!
Character development? Do you mean evolution of the character? Growth and maturation? Neither the Joker nor Palpatine have that; they're completely static.
Perhaps character development was not the right choice of words. I meant more how the character is developed in the story. How his character is presented to the audience and the overall effectiveness of this etc.
Themes? What about themes? The Joker's theme is the perpetuation of chaos, Palpatine's is the acquisition of power. Which one is more compelling? How do we determine that?
Through discussion obviously. But also by looking at the strength of their themeatic worth in relation to the text and how it relates to the audience.
Basically in the same way you think you can prove that Palpatine is the most powerful Sith I think I can prove that the Joker is the strongest character.
edit: Also the Joker is not the perpetuation of chaos, As I tolde you, that was a bunch of BS he was feeding Dent.
Aside: ZIM WILL RULE!