I already have the original one, which I think is 12"x12". JoAnn's online has both the 12"x18" and the 20"x23" on sale right now (with free shipping too, code SNP56). I really can't afford both.
The only negative I found about the largest one is that the cutting slots are very close to the carry hole and edge, which makes it easy to break. I think this one is hard acrylic also? Whereas the two smaller ones are flexible plastic?
Anyway, any comments to help me decide between the two larger sizes would be most appreciated!