FedEx all the way. They are way more helpful in trying to track a package, and way more apologetic when something goes wrong.
Plus, FedEx has *standard* overnight return on all C.O.D.'s, where as UPS sends your money back in 7-10 days. I use to run a business that involved C.O.D. returns, and there was now way I was waiting 7-10 business days to get my payment. Not to mention, I have a regional UPS warehpuse right down the street, and I have personally witnessed the "shipping specialist" playing parking lot football with any throwable consumer packages they could get their hands around.