How would humans lose against the zombies?
One thing that has always bothered me is how weak and slow the zombies are and that there's no way they could realistically win against well-armed human beings, especially in the United States. One person could easily go out and kill dozens of zombies each day. Ammo wouldn't be a huge problem either if you were disciplined enough to always go in for head shots and make each shot count. In some states like Alaska or Kentucky, etc. I would expect each household, on average, to have about 1,000 rounds of ammunition onhand. Slow moving zombies wouldn't fare well against those odds.
That said, I will always prefer slow-moving zombies to running ones. They're just so much creepier and give you a false sense of security. I especially loved the ones in the early 80's Lucio Fulci movies.