The only character DC/Warner has overdone more than Batman is Joker. Just give it a rest and try a different character for once. ANY other character.
Superman handily beats the Joker in terms of appearances, I think, unless you are counting the TImmverse, and even then, Supes is overdone there. Joker has been in Batman 1989, Dark Knight, and suicide squad (we can forget that). Phoenix will be the fourth WB joker.
BTW I don't get the idea that a Joker movie done in the style of Taxi Driver or King of Comedy is gonna suck, or shouldn't be done. Those are some damn solid movies. This Joker film is clearly inspired by those, and the Killing Joke, which is a pretty awesome Joker story.
I think in the last couple years, DC films have really upped their game, Justice League notwithstanding. We all know the MCU has kicked the DC films' ass, but they seem to be really trying lately. I want to believe this Joker movie will be a good one.