I have 3 different sized cutters but mainly use my 60 mm cutter. I find it more comfortable as I have arthritis in my hands . I bought the 28 mm when I bought my wavy rulers but so far haven't used them. (Note to self :- look into this.)
I also have a couple of 45mm cutters. One is my original Kai cutter as well as another Kai with an ergonomical handle which is comfortable to use.