I voted Jena, by virtue of my never having even heard of the battle before. But then, I've always been ambivalent (at best) regarding the Napoleonic Wars.
I read World War Z. It didn't do much for me. The movie was okay, but only very loosely based on the book.
I found the book a mildly entertaining read. I'll never pick it up again, but I don't regret the time I spent with it.
The movie was hot garbage.