Why buy square? It's simple geometry! For glass and ceramic kilns, a square kiln shelf will just fit more than a round one. A 10" square shelf will fit a 9.5" square and 9.5" circle. A 10" circular shelf can fit a 9.5" circle, but only a 7" square. Those pesky corners really get in the way! Front loaders are always square since they are easier to stack shelves in. It really is hip to be square!