If you don't already know, World War Z is a story about an interviewer who talks with people from all over the world as they share their story of what happened in the "Great Panic". Essentially, that nickname refers to the time period when a new disease struck the Earth, causing dead humans to come to life and attack every living thing.
The best adaptation for this story would have to be a TV series. My reasoning behind this is that a movie would not be able to come even close to covering all of the details displayed in the book. A television show would allow you to go in depth and actually cover most of the story that was told from all of the perspectives. The show would definitely have to show how the creation of disease and where it originated from (China), and also the path it took while spreading across the globe. It's acceptable to take out some stories from the book that might not carry essential information, but it's important to keep a lot of the stories to provide different views and backgrounds to help you fully understand how the world was reacting at the time of the outbreak. It would most likely be a benefit for the producer to also add in new scenes and stories to the show just to give it some originality and so that it doesn't follow the book exactly.
To make it successful, hand picking actors from recent shows that either are categorized as action or thriller genres would be a good idea because the story has a lot of action and heart-racing moments. I'm not sure that using anyone from the cast of The Walking Dead would be appropriate in the reason that fans might get upset that they're appearing on another zombie show. Though, I feel using a cast that has a background in thrilling and upbeat productions would really help to make the show successful.
For the soundtrack portion of the show, choosing songs that have a fast tempo or beat to it would fit perfectly into spots where it's a heart-racing scene. Though, slow and sad songs would also work well in scenes that display more emotion and heart-breaking obstacles.
A uniqueness about the book is that it's in the perspective of an interviewer, and that we never know who the interviewer really is. It's very important to capture the interviewing process in the show by allowing it to start out with an interview, and then fade into a flashback of the story the person is telling us. I also feel showing the interviewer at the very end of all the seasons would be a good way to close and recap the show.