I applaud Leto for trying something different, but in the end it just didn't work, IMO.
What made Heath's Joker so great is even when he wasn't on screen, you were still thinking about him and wondering when he'd show up again. I know I'll probably never like a Joker like I did Heath again, but I had hoped one would at least come close to or surpass Hamill or Nicholson at least.
If Leto doesn't get a lot of screentime in the next Batman movie or tries some even weirder s**t, i don't think his Joker will be remembered in the long run.
I liked it personally. But he definitely tried weird s**t that may not pay off if repeated too much. Like his lizard/creature thing he was doing in that room, with the guard. I also think he needs at least one more new laugh that is wild. Leto can pull a crazy laugh off, the videos are around from other movies he's been in. But he chose to just use that creepy, old man laugh that he uses quite frequently throughout Suicide Squad.
Ledger will go down as the greatest for a very long time. I can't see them jumping right into a new Joker as soon as they reboot (if Leto gets bad reviews in Affleck's film). They will need to be careful with who they cast, the design, everything. I can see them focusing more on other villains for a while.
Heath just had the right balance. There were fresh choices that were experimental and could have failed, absolutely. The ticks, the tongue, the voice...all ballsy. Leto made ballsy choices too. But Ledger always felt/looked more like a clown, still had a permanent smile, was really funny, didn't care about money or the mob and raised some valid points unlike Leto who so far is the classic mustache twirling Joker straight out of a cartoon.
Anytime i hear people saying Heath's Joker was the serious one and didn't bring that humor...i always facepalm.