Best Ever Joker

Yep, but he himself said that Joker is the role he's had the most fun with. A number of times he said he was retiring as the Joker but went back to the role for various animations and video games. His Joker voice is I think the most memorable. I couldn't even tell you who did the voice in the older cartoons (ie, Super Friends).

I don't know about Super Friends but he voiced Solomon Grundy in the Justice League series.

That I was one I was not aware of at the time, but as I always check the voice cast on most cartoons from the 90s. You'd be surprised at the names that turn up (such as Edward Asner as the voice of J. Jonah Jameson on the Spider-Man series). As far as Heath Ledger goes, I didn't care much for it. The makeup looked sloppy and he seemed less clownish, which doesn't quite work because clownishness was always Joker's trademark. It wasn't Ledger's performance I didn't like, it was the way character was written.

Who gets you vote then CrypticWizard for the best portrayal of the Joker (no voice actors) and why?

It's a toss-up between Cesar Romero and Jack Nicholson. As you said earlier, Nicholson had that fixed grin throughout the entire film, but I think he captured the character very well. Romero also had the essence of the character but since the 60s TV series was campy and not really what Batman was intended to be, he could be clownishly psycho but not quite as evil as the "true" Joker. If I had to choose...I'd say Nicholson.