If not the Penguin...

[riddler]

maybe the mad hatter since we know Burton did have a vision for the characte and alice and wonderland.


One thing we know is that Burton didn't read the comics (though his screenwriters did) so it likely would have been a character featured in the 60s series. That's why he wanted to use the 4 villains from the 55 film in his (riddler would have been his third film choice).

Riddler would have been deranged (big surprise) but likely not as eccentric as carrey; more of a plotter. I think he would have left more riddles, perhaps in the form of presents.

While I do think he would have done freeze eventually, I don't think the chrismas setting would have worked with him; freezing things in the winter isn't quite as effective.