Zombies > Vampires. Always.
Let's talk about why this is an indisputable fact of nature.
First, zombies are ruthless. Zombies relentlessly pursue their prey. They don't stop for pesky things like falling in love or severed limbs or being dead. Zombies only want one thing: living brains. They aren't worried about secret societies, power struggles, love, betrayal, redemption, or anything else that plagues the world of vampires. A zombie never feels bad about biting someone he's in love with, because that's not an option for a zombie. This makes them a superior predator in all regards.
Second, zombies don't yearn for adoration. Most of the vampire literature in existence focuses on their struggle between embracing their vampiric instincts and coexisting or gaining acceptance in a human world where they're feared and hated. Zombies don't have to worry about this. Why? Because they don't care whether or not they're accepted. Zombies have no desire to be loved, admired, adored, or respected by their human counterparts. Really all they care about is delicious brains. So while vampires are busy brooding about how to fall in love and how to cope with the loss that comes with immortality, zombies are gnawing through skulls and getting shot by the Marines. Zombies 1, Vampires 0.
Finally, zombies aren't immortal. While this sounds like it might come up as a plus for vampires, really it works against them. Think about it: vampires are immortal, meaning that they will be around, whining and being pale, for an indefinite period of time (barring something awesome like Blade getting out of tax prison and going back to wrecking shop on them). Zombies, on the other hand, represent the immediacy of the world we live in, as they pose an immediate threat to the human population. They are ruthless, diligent, and best of all, they can be dealt with. A zombie apocalypse has an end in sight, either when all the zombies have been dispatched or when the entire human population has succumbed to zombification. Either way, it's not an open-ended scourge, unlike vampires. So in a hundred years, we're still going to have to deal with vampires writing bad poetry and brooding and wearing stupid clothes, whereas zombies will have come and gone without subjecting us to their emotional vulnerability. I look forward to the day when zombies discover they can feast on vampires, killing two birds with one stone.
In conclusion, zombies have always been and will always be the superior undead scourge, and it's time they regain their terror-inducing prominence amidst a growing obsession with pretty-boy teenagers who wear body glitter.