This isn't about the current storyline, but it does have a little relevance.

Parallel Universes where the villains are heroes and vice-versa are always interesting because you get to see heroic Jokers, villainous Batmen, and heroes as anti-heroes. When you think about it, the line really blurs between good and evil when you see how the choices people make under certain circumstances define them. When you don't know their backstory, it becomes fascinating to watch known psychotics rescuing people.

Take the Justice Inc. storyline. Parallel Captain Heroic would not be an anti-hero vigilante if he chose to serve Justice, Inc. but the fact that his parents separated over the corporation says something.

For a more mainstream view, take a look at the idea of a villainous Batman. Everyone knows that Batman fights criminals to avenge for his parents' death; what event in his life would change it so that he would be against justice and the law?

Just something to chew on.

I voted for the Joker and as I considered the options I thought I would see a lot of Joker votes. I think it would be very interesting how someone as criminally insane as the Joker could be written as the hero in any story. (and this is regardless of whichever continuity you would choose to place him)

Agreed, but then there are villains like the animated Slade from Teen Titans. He terrorizes them for two full seasons, returns for a third helping in Season Four, but then helps them fight off Trigon, even saving their lives several times. He does it for selfish purposes, but seeing him as a character we could root for was interesting.
Syndrome is also interesting because on some level he wants to be a hero; he just hates other supers because he has no powers. If he had been given the right nudge as a kid (as opposed to a brush-off) his technophile skills could've been put to good use.

Wouldn't a heroic Joker just be the Creeper?

Possibly. But it depends on which interpretation of the Joker you take. You can have a clown with a taste for laughing gas, a psychopath who creates chaos for fun, or even just a colorful thief.
I've only seen the Creeper on TNBA. The difference, though, is that the Creeper has an alter ego that he can release. Joker is always the Joker.
But it's possible. That's why they put him in that episode.