I have the best luck with either UPS or FedEx, and I have never had a damaged firearm with them or USPS. My bone with the Postal Service is that the clerks, at least in my area, are usually not aware that an individual can ship a firearm. I usually stand at the counter while he/she get the supervisor, who at times has to look it up.
My UPS depot is great, fast and efficient, at least a far as I am concerned, and the tracking, unlike the USPS, is usually spot on. I think the Postal Service tracking is terrible, usually not indicating an update until the package is actually out for delivery.