I haven't used anything but USPS, since shipping rates for small volume customers are insane with UPS/FedEx. A box that costs $5 shipping anywhere in the US, costs $35 with UPS and $40 with FedEx, and the shipping time is longer. International shipping for a medium box was $49 with USPS, it was $150 with UPS and $190 with FedEx. Unless there is some trick I am missing.