I choose UPS or FedEx because USPS cannot truly overnight a package. Their "next-day" service is a guaranteed 2nd day service. There is no way they can get a package to me (in the midwest) from Florida or even Illinois the next day. It's always the same thing- guaranteed 2nd day delivery. My last order was from only 300 miles away, and they still couldn't get it to me overnight even though it was on it's way before noon the previous day. Their tracking service is a joke, too. If you want to find out where a package is at, forget it, they'll only tell you when it left. UPS and especially FedEx give you the whole story. I got an overnight package via FedEx yesterday that didn't leave it's origin until 10:30pm on the 3rd, and it was in my hand at 9:45am on the 4th. That's 11 hours and 15 minutes. Granted, it was from a neighboring state, but there is no way USPS can come anywhere close to that kind of service.