Do you have data for the delivery success rates of each carrier? I have been looking for that, in fact, and wouldn't make any blanket statements outside of personal experience without it.In your use case UPS may very well be better, as above there are just as many people who have issues with FedEx. Another consideration, would be contacting the shipper and requesting your preferred form of shipping. Saying broadly "X shipper bad, Y shipper good" is just a fallacy if you have customers across the country as the two major players here have nearly identical delivery success rates.
I'm kinda also baffled as to why some folks get so passionate about someone saying they're frustrated with a carrier over another. Do you work for FedEx?
Edit: Below is my initial vent. My goodness, I said nothing inappropriate in it.








