I have no problems with my Omnigrid rulers and have them in many sizes. I use the clear medical tape (NexCare) on the backs to prevent sliding.
My absolutely favorite ruler of all times is no longer made. It was called 'Fingerguard" and was made by a lady in Maine. Unfortunately, she has gone out of business. Crisp clear measuring lines and a guard (runs the length of the ruler) at the 1/2" line (1/4" line very clearly marked) to keep your fingers away from the rotary blade. Wish I could buy more of these rulers!