Generalizations. Hmph.
I suppose if you are unfortunate enough to get into a claims situation, then that might be a matter of corporate approach. Otherwise, I think it depends more on the people you happen to get involved with (as in most things).
I've had packages completely disappear from both FedEx and UPS tracking for a couple of days, and when I call to ask, they usually say well, it's just a best effort, we don't guarantee the tracking info to be complete (okay, so how do we trace it when it doesn't show up???).
In my personal experience, UPS seems a little more likely to deliver a box that looks like an accordion, but that may be partly due to shipping heavier things through them.
On the plus side, anecdotally, there was a time when I missed a FedEx delivery by minutes. I called them up, and they arranged for me to meet the truck at a later time that day, about a mile away.
And when my $5000 hi-fi preamp failed to return from repair (in the same shipment with my CD player), I went to the local UPS depot and some guy walked me around through the lot, checking the three possible trucks that had serviced my area that day. No luck... but then after 7:30 that night, a UPS truck drives up. They guy, who sort of knows me, said he was just finishing up, saw that he had this package that wasn't supposed to be on his truck/route, and thought it might be important (yes!).
I'm not defending them, and don't really trust any of them. Fortunately I'm close enough to drive my Alembic myself, and I can't contemplate shipping it or even flying with it.
But for those of you advocating USPS, remember where the phrase going postal came from. Maybe they're better with claims, don't know, but no matter who you use, you might run into a bad conveyer belt, someone who had a fight over breakfast and put a little extra adrenaline into moving your package, whatever.
Yeah, karma, that's it.