After the Joker, Who Is it?

Bane? Penguin? Hugo Strange? Who?

Bane I guess.

Tough ! I think Ra's Al Ghul, Hush, Hugo Strange, Two-Face, The Riddler, Wrath and Bane all qualify for second place. The others are not Arch Nemesis, they are just simple vilains that happen to live in Gotham (Poison Ivy, Penguin, Ventriloquist, Dr Freeze, Victor Zsasz, Killer Croc, Mad Hatter, Scarecrow, Black Mask, ...)

Bane or R'as al Ghul.

Bane. Easy answer. The dude is one of Batman's most iconic villains

Ra's or Bane.

@worldofthunder: Yeah that's true but if given the time on comics Wrath could also become Batman's one of the arch nemesis

Ra's al Ghul

Bane or Ra's leaning towards Bane because of the broke the Bat and how similar they are .

Bane for sure

Ra's al Ghul. But it's a close one with Bane.