5. Teen Titans
For one reason or another, 2003's Teen Titans seems to have the most dedicated fanbase of all DC's animated shows. It makes sense too, given just how good the show was in its prime, but one would surmise that the continuation of the series in the 'Go!' format is probably responsible for the its nostalgic resurgence in recent years.
Revolving around the likes of Dick Grayson's Robin, Starfire, Beast Boy, Cyborg and Starfire, Teen Titans offered audiences a delicate balance between straight up silliness and a more mature and thoughtful approach to superhero storytelling. The show did have its cutesie moments of course, but it's important to remember that the involvement of Ron Perlman's Deathstroke (dubbed Slade in the show) often led to some pretty dramatic highs and lows. The series finale, too, laid on a lot of emotion thick and fast. Fans of Starfire and Robin have never quite recovered.
It may not have succeeded in quite the same way as that other adolescent animated series, but Teen Titans was a standout success for a reason.