Unless the center of the quilt is directional (like a panel) I would make all their feet either point in to the center, then miter the corners. This way, every way you used the quilt, part of the border will be correct. If the center is also directional, I would make all the borders face the same way. So you would cut some along the length of fabric and some along the width. I'm a bit anal, and have a background in garment construction, so I would buy extra and match the print to disguise the seams.