They have yet to deliver anything as good as Jack Nicholson (or Cesar Romero for that matter).
Jack Nicholson's Joker I don't think has aged as well as people think, because really it's just Jack Nicholson being Jack Nicholson, in makeup.
Romero on the other hand doesn't get nearly enough love.
To be honest, Hamill is and always will be my favorite Joker, with Ledger closely behind him. That being said, I think it'd be a rash move on anyone's part to judge Leto's actual performance on one photo alone. Clearly they're going to sell the insanity factor as much as possible, judging by said photo, but come on.
Suicide Squad Joker in the comics is wearing someone's fucking face.
It doesn't get much crazier than that.