The second has a better balance. BUT, if you prefer the first one because of the single black in the center, perhaps you could swap the 'solid' circle in the upper right corner with the 'thinner' circle that is directly left of the center. This way the center row would have more bold center and maybe appear more balanced. As for quilting, if the squares are small enough, I would probably just do an echo around the outside of the circle. Either a variegated to match the print on all or use a black on the black. I really like the circles on the black, very different.