6x24 for me. Folding the fabric an extra time is another place for the seam line to get wonky (if the fabric isn't folded exactly straight). After that, I use my 9.5x9.5 for almost everything, and I could happily manage with just those 2 rulers (I do have a few more, however). I have two 24x36 mats on my table, running 36" back from the front so the 24" ruler fits well, as long as I don't have a pile of junk at the back.