I've worked in a few different pizza places in my day. Most used the circular roller cutter but pizza hut had my favourite cutter. It was a long rocker blade (curved so that it's taller in the middle then you place it and "rock" it from one side to the other to make the cut).

Rollers or anything that slides the blade along the pizza will pull cheese and toppings along with it and will only cut as straight as you keep it. Plus, if you realize halfway through a cut that your line isn't very good (like you're about to cut some pepperonis in half and probably drag at least one part off the slice entirely when a slightly different angle would have gone between two pepperonis), you're kinda committed to it already, while a rocker blade allows you to see the whole line easier before you start the cut.

I don't have one at home though because it's not very practical to store and only really worth having if you're cutting a lot of pizzas and flat breads. It could work for cake, too, though it depends on how high the cake is.