4. Superman: The Animated Series
The immediate follow up to Batman: The Animated Series, and the beginning of the DCAU too, Superman: The Animated Series did for the Man of Steel what BTAS did for Batman. There's not much else to it, really.
STAS offered what was the defining image of Superman to a generation of kids fist tuning into their television sets, and the series, written with the involvement of Timm, Dini and Burnett, was utterly fantastic. It presented a version of the character that, whilst indeed powerful, seemingly lacked the capacity to do the craziest feats his comic book incarnation originally could. Super-strength, flight, heat vision and ice breath were all included of course, but this Superman really had to work for a victory.
Adding a sense of vulnerability to the Man of Steel was by far the best thing Timm, Dini and Burnett did for him, and the character's subsequent development into the all-powerful hero we're more familiar with in Justice League was massive - a creative process that spanned almost a decade.
The show's art-style was also definitive. Much like BTAS, it crafted a version of Metropolis that was equal parts timeless and modern - an image of the city that was, in part, inspired by the aforementioned Fleischer productions of the forties. The addition of Batman in the World's Finest special was also a welcome treat, and a film that people should track down if they're after an enjoyable Batman/Superman crossover.