Imo, AA has
- the best level design
- the best atmosphere
- the best story
- the best riddles
- the best villains
out of all Arkham Games.
And don't forget the scarecrow scenes.
Well and there is just Batman. No Robin or Nightwing crap
Aside from level design, whether these are good or the best of the series is subjective. And even with level design in Asylum, there's never any clever gating of progression and it's all laid out for the player except for cutting the bell in the bell tower and gliding back down. Even areas in Arkham City require more thought and player input to traverse (e.g. Sionis steel mill and the ice grenade platforms, or Penguin's flooded museum). Compare it to a Metroid game (even Metroid Prime with hints turned on) and it's clear the only similarity to those games is backtracking, yet that's is all though linear hallways and static rooms that occasionally get repopulated with a handful of enemies with nothing the player has to figure out on their own. There are points of interest (e.g. the botanical gardens) splayed out on the map, yet are connected by those hallways — you have to run everywhere, occasionally having the grapnel up to a vent. The map same in Arkham City — points of interest in a hub — but just without the restrictive hallways. It's really boring, even on the first playthrough, to not be able to use the grapnel to get the roof of the building outside the front gate, or to have to go back through the Asylum that is completely devoid of anyone except for the warden and Clayface.
If the level design was interesting, it was never standout or special enough for the game to be the obvious answer in the matter of "which Arkham game has the best level design?" unless you believe linear level design is always better than more open level design, no matter what. I sure think the concept of the game is fantastic, but that doesn't change how formulaic it gets even the first time through.
And at least for some of these things listed in your post, I can understand why someone would like them most. However, even if I can see why someone would like the featured villains the most, that doesn't mean it has the best boss fights. If it had the best riddles, it doesn't mean it has the most clever implementation of the Riddler. If it has the best hallucinations, it doesn't mean the Scarecrow stealth segments after those are good, and so forth.
To say the implementation of Riddler riddles/trophies is better than in City, the encoutenr design better than in Knight or that the boss battles or story is actually better than that of any of the other games just doesn't hold much water when AA is fully assessed.
talking about trophies/achievements :
anyone has done the 8 jump thophy? i´ve done all 16 available in gotham and nothing....very weird!!
i also notice the amount of space left in the Arkham Episode section which leads me to believe that at least more 3 DLC single player packages are coming out , if so which villans would you like to see?
My take :
Mr. Freeze
Killer Croc
Bane
You have to travel 100 meters with each jump, so place a marker at about 100 meters away from them so you'll know yo umade it.
There's a list of villains people found in the game's files somewhere, so that list is all but confirmed now. I won't spoil it, but it's floating around somewhere.