USPS is the choice for me, and is by for the least expensive for most etsy sellers. Fed ex and ups give the most breaks on commercial delivery, and most etsy sellers, like myself, are shipping individual items to residential listings. The cost, convenience and security can be shared by seller and buyer in this way (If it costs less, the buyer pays less!!) the irony is even of one ships by ups or FedEx, they also use the post office in many legs of their journeys, especially to rural or outlying areas. So even if you ship via a different carrier, the item can sometimes still spend a little time in a USPS truck!!!