I find it sort of ironic that a lot of the time, USPS is the fastest and cheapest option for us here. I sell a lot of music stuff on Reverb and almost always ship Priority — sometimes it's a little delayed, but I've never had anything flat-out lost and most of the time it takes just 2, 3 days max. Meanwhile I shake my fist anytime I order something and it ships to me via UPS or FedEx Ground.
I will say though — UPS and DHL International are f'n incredible. It never makes any sense to me that stuff can get to me from outside of the US in 1 to 2 days, yet domestically it can be a real shitshow.