An Array of Complex Characters
There is nothing worse than a character that fits too snugly into a stereotype. Especially in a super-hero based film or show. It is always made crystal clear that the villains are villains and the heroes are heroes. But there is never enough time spent on highlighting the inconsistencies that make us human. 
A beautiful thing about this series is that the characters breathe and bruise the way we do. Even the bulletproofed Luke Cage is at times distant, cold, selfish and unconcerned with the issues of Harlem. Meanwhile Cottonmouth, and Mariah the main antagonists have conflicting moments. They experience regret. Every main character in this series is battling something. That fact alone makes the series a compelling watch.