USPS, FedEx, UPS in that order.
This. Priority Mail is fast and reliable, and the packages are gently handled.
USPS and FedEx both deliver on Saturdays, putting them ahead of UPS.
FedEx has a comprehensive selection of cartons in all sorts of useful sizes and shapes.
UPS won't insure any packages unless they pack them. Ripoff. Not a problem with USPS or FedEx.
When ordering from Canada, UPS sends the packages through US Customs, and charges you a hefty broker's fee for doing so. There is no requirement to send Canadian packages through Customs, who doesn't even look in them. I just request the packages be sent by Canada Post. When they cross the border, they automatically transfer to USPS, who brings them to your door. Another UPS ripoff.
I ordered a roll of address labels from Office Max, for my office. Office max sent them via UPS. They didn't arrive. Instead, I received a post card claiming they couldn't deliver them because I had moved. I had not moved. Note: they managed to get the post card to me (via USPS) but could not get the address labels to me via themselves. I drove down to Office Max to see what could be one. They determined that UPS had returned the address labels to Mankato, MN (where they evidently are made), and asked that they be sent to my office. Once again, I got a post card telling me that I wasn't there. I had to drive downtown to the UPS office to get them.
Note the irony here. It was a roll of address labels with my office address on them. UPS didn't want to believe that bringing them up to my office suite with the same address and suite number as were on the labels, as well as on the package containing the labels, was the right thing to do. But they could believe that if they sent me a card to that same address via USPS, it would get to me. Which it did.
Phooey on UPS. Double Phooey!