I had to do some experimentation. I wanted a one-way rental, but had to search for the right city pair. Auto Europe offered the best price as well.
About the service from the local car rental company - KEDDY
Both the Swansea (pick-up) and Chester (drop-off) locations had a friendly, professional staff. I was a little nervous starting out as an American on left side roads, but the staff treated me as if I were one of their regular customers, which was calming (all went well). The car was in very good shape and served us well in over 1000 miles of twisty Welsh roads.