I like the Creative Grids squares--2.5, 3.5, and 4.5" ones I use. The lines are thin, and don't create a shadow for me. (I think it's my astigmatism that bothers with the other rulers.) The also don't slip as much. I've tired using exact sizes for smaller cuts, but find I am more accurate using a little larger square as it allows more finger space for me to hold down! (LOL do I have big fingers?) Good luck!