I have two ideas for a book, need help deciding which idea to focus on?

They are both about a zombie apocalypse, the main character is a man named Mike (in both versions). The FIRST idea: The zombie apocalypse happens, and a band of friends have prepared for it. It details their escapades over the years as they try to rebuild their lives- and the world. This is more of a series-type of book. The SECOND idea: The zombie apocalypse occurs, and Mike is one of the first casualties - but he's reanimated as a zombie. This would detail everything, how the accident occurred, how he lives, how he thinks, and perhaps his attempts to make himself human again. Please tell me which one you like (#1, #2) and why, and any improvements I could make. Once enough people agree on a storyline, I'll start working on it.