Eleanors rulers usually give you the opportunity to square up, so if you're not great at the quarter inch seam there's room for error. But the down side to her ruler would be you need more fabric and her rulers usually only have one or two different sizes that you can make with one ruler. Zimmermans ruler comes with many option for sizes but requires a bit more accuracy in piecing. I personally have Zimmermans rulers. It really all comes down to how comfortable you are with your piecing and the instructions. I think I would watch a video on each ruler and decide which one works best for you, they all are great, just a tad different.