Basically you have to choose a "Universe" but I tend to go with Romero since he kind of started this Zombie shyt and has a gang of flicks in his series(?). He had a partner for Night of the Living Dead but they split and the other guy got the name "Living Dead". Return of the Living Dead was one of my favorite movies, but it is campy as fukk. Romero stayed with the "serious" zombies then you have people like Max Brooks who also wrote about the same type of Zombie. World War Z was nothing like the book BTW. They could have called it something else and I would have had no idea they were trying to adapt the novel.
*Digresses*
Romero Slow Zombies FTW. You'd have like a half a day to get sick and all that. Or whatever amount of time would be most effective storywise but not immediate and not more than a couple of days.