Just my opinion, but 1st Class Mail and Priority Mail are something of a bargain. I’ve shipped a good bit of stuff (several hundred items) and never had a single problem.
Now, Parcel Post and Media Mail are a different story. If you’ve got a relatively small parcel and are thinking of Media Mail, go ahead and pay a little extra and ship it First Class or Priority Mail. If you’re thinking of shipping a larger item Parcel Post, forget it, ship it Fedex Ground.
I use Priority Mail to ship from home on a daily basis. I have done it for years and have never had a shipping related problem. The carrier picks the packages up at the door or in the mailbox and there is no extra charge. They also provide the boxes for free. That may change soon though. I used to use United Parcel Service but the driver used to complain right to my face when he had to pick up packages at my home. I even paid extra for the pickups. I also had a lot packages destroyed by UPS. Not too much experience with Fedex.
The real bargain is the flat-rate box. I can get 70 lbs. of lead bullets shipped for $14.
My pet peeve with the USPS is their lame tracking system. UPS and FedEx will tell me exactly where a package is. Ever try getting delivery confirmation for first-class mail? Either you suffer through antique, arcane “Certified’ mail with no tracking or spend big bucks for priority with delivery confirmation.