I have a friend who delivers for USPS so I know it's super stressful at first, he hated it and wanted to quit for a while but he's still doing it I'm pretty sure. It was just unfortunate that the same day I had a live animal box was also that person's first day and resulted in a late delivery. Just an unlucky combination. I don't blame them for the lateness (though I was a little miffed by their casual comment, but I was already kind of worried I was going to have to return a dead fish that I wouldn't be able to get an exact replacement for since it had a unique pattern, so I probably was more bothered by it than I usually would have been). I was also a little bothered that they didn't hold the box at the post office like I thought they would, I drove out there minutes after they opened that morning but it was already gone. In the end though it all worked out.

That being said, USPS has always been my favorite for packages. UPS is consistently late for me and Fedex is, well, everything this thread has been describing. I always ship USPS and thus far nothing has ever gotten lost (did have something returned to me once that looked like it got run over by a truck or something, had the postage purposefully ripped off, box loosely retaped, and someone wrote "needs postage" on it as if the postage was never there. The post office employee I went to about this was the one who processed the box originally so he knew it had postage on it when sent so I was refunded and it made it to its destination the second time around). For the most part, it's very reliable and I send out so many boxes, the post office desk clerk knows me by name and my package preferences by heart.