Great quilt :) Colors from the quilt top should be carried over into the border. The yellow seems to stand alone.
Maybe a narrow border in a darker solid color (to separate a pieced border) carried from the quilt top. Then maybe add a pieced border the same as your squares in the quilt top. This pieced border then will tie the quilt together. Lay a few fabrics (maybe a red or a blue) along side the quilt covering the yellow border and see the differences. I would make my binding the same color as the narrow border. This is just my opinion and what I would do. But it is your quilt, the final decision should be yours. :thumbup: