i have quite the opposite experience. UPS always delivers and they deliver on time. USPS on the other hand are a bunch of lazy good for nothing shitheads who don't ever deliver any of the packages i order. instead they instantly post the damn notice saying to pick it up at the post office. in fact i ordered a knife online and the damn post office claimed to have shipped it back to the knife store i ordered from with the excuse of my house being undeliverable. upon filing a complaint to the post office, they decided to deliver my knife and i received it the following day.
I once sent a tee shirt to a friend who lives in Mexico... cost me 80 bucks to send it via UPS.
I was gonna send it via the USPS, but my buddy told me that once the parcel was in the hands of the Mexican postal service, most anything was liable to happen to it. That is, there's a lot of theft in that system, along with generalized inefficiency. And so I sent it via UPS.
My friend sent me a gift in exchange, but he didn't go to UPS or the Mexican post office, and instead gave it to his mom as she left for Germany... which is where she sent it to me from.
Sometimes, ya just got to go with whoever can actually get the job done...