I work for a company that ships about 1000 packages a day via Fed-Ex Ground (RPS), UPS, Airborne, DHL and several other carriers, and I have found that the ground services are very similar in the number of packages that are lost or damaged. You will find just as many people who hate UPS (www.ihateups.com) as you will who hate Fed-Ex. The safest way (albeit expensive) is to ship either Next Day or Second Day. There are very few mess-ups with the "rush" carriers.
-Kurt
-Kurt