All wonderful entries!
I agree with TWD being a 'universe show' as well as 'living breathing comic book'. It also (for me) has added dimensions to the Zombie/Horror genre that hasn't been developed in past movie vehicles through it's unique characterization and character dialog and action interplay.
The only other close approximates (for me) are in movie form: 'Juan De Los Muertos' and 'Shaun of The Dead.' Comparing those things altogether the universe is the important container and the characters adapting and evolving from it and their interplay are what make the journey worth it.
Indeed Robin, a dark dark place where we can watch humanity thrive or languish.
My favorite episodes actually have little or average use of zombies 'TS-19' and 'Clear'.
Lost had a way of leaking out the purpose of why they were on the Island slowly over time.
The purpose of The Walking Dead (from the producers perspective) may have been intentional undefined, and left to be subjective.
Living Comic book:
Michonne's sudden appearance from one place to another (from the ground to the Morgan's rooftop and her fast extraction of Carl's photo) during 'Clear' and the effortless way she wields her Katana most of the time bring that point to life for me.