I have an older (bought in 1988) paper cutter I bought from a stationery store - a big, heavy thing, built of metal so to last. It has a flat rod running across the board with springs at either end. When cutting paper, I press down on this rod with one hand and it flattens the paper, so ensuring a perfect cut.
I've not seen these monster cutters being sold new for a long time, but they can be found in secondhand and/or charity shops.
I also have a smaller, much less heavy and newer rototrim cutter which does its work 80%-90% to my satisfaction, but often fails to give a perfectly level slice.
Older is definitely better. So says my partner...