Very tough to choose just one, but I deeply enjoy Batman Adventures vol. 2 #05.
*Deadshot's first and only appearance in a Batman animated book (after appearing just once in the Justice League cartoon)
*Eel O'Brien as Batman's informant
*Bruce finally ready to settle down
*The retrospective on the various loves of his life
*Bullock and Batman team-up
*Mayor Cobblepot's freaky fetish
*Batman arresting Julie Madison (losing love again) and her recognizing his voice as Bruce
*The return of Phantasm
It, like the majority of Batman Adventures, is as good as an episode of the cartoon.