In one corner, we have "Book of the Dead: The Complete History of Zombie Cinema", by Jamie Russell! Weighing in at 352 pages, this covers the entire history of the zombie film from its origins in Haitian folkore all the way up to 2005! And in the other corner, we have "Zombie Movies: The Ultimate Guide", by Glenn Kay! Also weighing in at 352 pages, this book reviews virtually every zombie movie made from "White Zombie" all the way up to 2008! But let's face it, fight fans--only one of these guides has what it takes to sit on your bookshelf! Let's look at the tape.
Kay's "ultimate guide" does, in fact, have some ultimate-ness going for it. He covers loads of obscure zombie movies from all over the world, including Hong Kong and Japanese zombie cinema, Italian and French zombie movies, and even some TV shows with zombie episodes (albeit some more thoroughly than others.) But unfortunately, he doesn't seem to like any of them. His introduction says that unlike certain other pretentious guides (a not-too-veiled attack on Russell's book, which came out first), he's not afraid to have a few laughs at the cheesier of the films. But the "laughs" mostly take the form of pointing to low-budget film after low-budget film and saying, "Hey, doesn't this one suck too?" He gives Romero a free pass (citing film after film for "cheesy zombie makeup", but ignoring the slapped-on gray paint in "Dawn of the Dead"), but anything else that isn't a major release (or something he watched as a kid--certain 80s films get far more love than they probably deserve) is something to look down one's nose at. I'm not saying that a film like "Hell of the Living Dead" is an instant classic, but if you can't find joy in quirky, low-budget films, you probably shouldn't be writing a zombie movie guide.
Plus, he's oddly slapdash about his criteria for a zombie movie. The "Evil Dead" trilogy is put in the back of the book, because they're not "real" zombies, just victims of demonic possession (I got news for ya, Glenn. Henrietta was buried in a cellar for two weeks before the start of "Evil Dead II". If she wasn't a zombie at first, she sure as heck is one now.) But "28 Days Later", with its decidedly not dead undead, is put in the main guide. Similar inconsistencies plague the whole book. (Plus, he gives "Slither" a bad review. This is not only a sign of his lack of taste in zombie movies, but also a sign that he secretly hates babies and kittens.)
On the other side, Russell's "Book of the Dead" suffers just a tiny bit from being dated--it ends right around the point of "Shaun of the Dead", which was really when the recent wave of zombie horror kicked off, and so there are a lot of fun recent movies it omits (like "Quarantine", "Slither", "Diary of the Dead", et cetera.) But it more than makes up for this by being just as comprehensive about the period it does cover as Kay's guide, if not more so, and by covering the entire history of the zombie in cinema instead of simply covering each of its movies piecemeal. The shot-on-video trend in zombie cinema is covered in depth, along with the way that different landmark zombie movies (such as "Night of the Living Dead", "Return of the Living Dead", "The Evil Dead") transformed the genre. Yes, he does get into the symbolism of the zombie, an act which some might see as "pretentious". Others of us like to think of it as "intelligent". Best of all, he has passion for the zombie film--silly low-budget movies like "City of the Living Dead", "The House By the Cemetary", or "Zombi 2" are held up and examined for their good bits as well as their bad. He's not indiscriminate, but he's no snob, either.
Ultimately, I think if you can only afford one, go with Russell's "Book of the Dead". If you can afford both...then buy Russell's book, and save your money to go buy some of the DVDs he recommends. You won't really be missing anything if you skip Kay's book. It may be "ultimate", but it's not actually much fun.