A lot of it has to do with your local terminal and drivers. Here UPS makes their delivery date probably about 60% of the time as where FedEx is more like 98%. FedEx delivers on the weekends as where UPS delivers on Saturday, sometimes. Here both have pretty good drivers as far as "setting" the package on the porch. Most even ring the door bell. FedEx has always found my address. UPS, no. At lease that is what they say. I think the driver gets jammed up and doesn't want to work late.
Go to the next city over and everything could be flip flopped.
My experience is if I order the same part from the same place in L.A and they both ship on Monday. One with FedEx and the other with UPS I'll have the FedEx one on Wednesday or Thursday every time. The UPS one maybe on Friday but a good chance it will be Monday.