I've worked in the shipping industry for the last 10 years or so, and have been the shipper, receiver, package handler, and delivery guy at various times. I have plenty of experience with USPS, UPS, and FedEx. I can confidently state that they ALL break stuff, lose stuff, deliver stuff late, and just generally screw up things. ALL of them sometimes lie to you on their tracking system, on the phone, and in person. And sometimes, they ALL go the extra mile to help you out and get things fixed. They ALL overcharge on one service or another, and they ALL have the best rates on some other service. They are ALL a pain in the butt sometimes when you need to process a package claim, and they ALL just pay with no hassle sometimes.
What it all comes down to in the end is the specific employees that are involved with your particular package; not the company your package happens to be travelling with. Each company has idiots that got fired from the McDonald's drive-through, and each company has super-geniuses that prefer working outside to rocket science. In the end, all you can do is choose the company that has the best pricing for the specific service you need, pack your box really, really, really well, and then hope for the best.