I have two pizza cutters. One of them is better and slices through pizza quite easily. I have used a knife before, but the pizza slides too much for my liking, or I use a fork to hold it still and then it rips apart as I saw through it, so I try holding it with my hand and burn my fingers. I suppose I own a butcher knife, but I've never actually used it, it's hidden in a drawer somewhere. I don't like using big knives, they are kind of scary. I guess I watched Final Destination too many times.
Anyway, pizza cutters are super cheap and cut pizza well (as the name implies), so I've never thought about using anything else.