I've had cars transported about 5 times. Believe it or not, the 2 good experiences I had were with Ebay's affiliated and recommended shippers. The other 3 experiences were not good, but were acceptable given what I was shipping (beater project cars).
I'm sorry, but I don't have records of the two outfits I used that were good other than they were contracted through Ebay. In both cases I was able to ask that my car be loaded by the seller and be the last car in, and that I be able to unload it myself on delivery (as opposed to them moving multiple vehicles to move mine). This cost more because it dictated the route and how full the transporter could be. Essentially they had to come most of the way across the country, drop my car off, and then drop a few more off East of me. I suppose this could have meant I would have to pay 3 or 4 cars worth for my one car, but it wasn't that bad ... the seller and the shipper worked with me on waiting for a week when the transporter was already coming East, and had a few cars to deliver all East of me anyway. I think I paid about $800 to get the car from TN to OH, and agreed to meet the truck driver somewhere convenient for him instead of my driveway.
I looked into "one car in one trailer" transportation and it was so expensive I could have bought a better car locally for the difference.