Creative Grids wins hands down. I am replacing Omnigrids for several years now with the C.Grids rulers, i like the visibility of the lines so much better. And they are a bit more non-skid. The 6x12 inch and the 6.5x6.5 ones are the most used. I also have a 12.5 x 12.5 someplace for squaring up but I measure and square up the *increments* of a block before final assembly, then just lay the 6x12 ruler over the block as I do the last seams, to make sure its what it should be.