This is first comic in this series. It is very good and shows how Justice League acts when faced with the zombie apocalypse.
A Good Day To Die focuses on the less important superheroes like Booster Gold and Mister Terrific during the apocalypse.
Unkillables is like A Good Day To Die except about villains instead of heroes.
Hope At World's End is the only digital exclusive of the series.
Dead Planet is the most recent of the DCeased series. It follows the citizens of Earth 2 as they react to the zombie apocalypse on Earth 1.