Nightrunner, the Catwoman team-up in Japan, Stephanie Brown in Leviathan Strikes was certainly one of the best issues or at least if it had been an issue it would have been one of the best.
Probably just for shock and awe the return of Cassandra Cain under a new moniker got my vote. Despite not being that important or featured. Just by principle.
Though KATHY Kane, Kate Kane. INC has had just some of the best stories from Batman. The whole run is wicked cool.