I absolutely love Dark Knight and Heath Ledger’s performance of Joker. I haven’t watched Suicide Squad yet (thanks to all those negative reviews, but it is on my to-watch list anyways) but I can never think of any other actor doing the role of Joker. For me, Heath Ledger will always be the best Joker. And I am sure a lot of people would also agree to it.
I found a video today which explains why it isn’t just the performance of Heath Ledger that makes the Joker of Dark Knight so powerful. He is, as is explained, only one side of the coin. He is the reason Batman becomes more powerful and more wiser. He is one of the best antagonist as a character goes in a story. Check out this video for more details.