Love Omnigrid! I have the nonslip film on the backs of some of them. I like the fact that they have black lines (visible on light fabrics) and yellow lines (visible on dark fabrics) on them.
I don't like the rulers with ridges on the back that prevent you from sliding the ruler without disarranging the fabrics on your mat. The film on the back of the Omnigrid doesn't stick until you have the ruler in place and press down on the ruler.
I use my 12 1/2" square most, but I have been enjoying my 3" x 18" ruler lately. I have a lot of rulers!! :lol:
I'm not crazy about the other long rulers with the 1/2" added, like the new 6 1/2" x 24" ruler from Omnigrid, because I like to be able to measure from either edge without doing complicated math.
I started with the 5" Olipfa, 20 years ago!