My Martelli is my favorite but you have to use the right type of blades in it--the Olfa type make it wobble--Fiskars will work. The reason the Martelli is my favorite is because I can control it easier and it doesn't tire my hand & shoulder out like my Olfa's do. I only have the 45mm version of the Martelli so I switch to the Olfa 60mm to square up quilts and cut batting. For long cutting sessions--you can't beat a properly maintained Martelli. For quick jobs--whichever one I find first in my mess will work--LOL!
katz--There is a lefty version of the Martelli. Red is for righties--black is for lefties. Which one did you try? Also, did it have the correct type blade in it? I actually cracked one of the Olfa blades in mine because of the wobble problem when using the wrong type.