Why, indeed. You were told to stay out of this topic, as I recall, and yet you keep coming back and looking for ways to subtly insult or downplay Ledger and his performance. There is a Michael Jackson thread on the celebrity forum that I read from time to time, and even though I think he was the world's greatest dancer, I don't think he was that great of a singer. Nevertheless, I keep my textual mouth shut out or respect both for him and, more importantly, his fans who post there. It's not my place to say negative things about him in what is pretty much a tribute topic. This seems to be a concept you do not understand. And, as a matter of fact, if you read the opening post of this thread, you're pretty much off topic when you do such things.
Whether certain roles are better than Ledger's in TDK is a matter of personal preference. Some might think J-Lo's performance in Gigli was better than Ledger's Joker. It doesn't matter. There are other places to discuss such things.