I have the 12-13" square one, seldom use as I haven't sufficint room to turn it, thus making it useless.
I also have the round one from Come Quilt with Me which I loved; wore it out and it's practically doubled in price so didn't replace.
Found a square 6 or 7" Fiskars at Joann's; love it and with the coupon it's under $8.