It has always been my view that where you live informs preference. For example, I am a long way from the FEDEX hub, so it is very common for shipments to be either late in the day or left at the local FRDEX store. UPS WorldPort in Louisville is the transition point for all overnight shipment to me, so weather there dictates reliability. Both are generally OK, but I have a slight preference for UPS. USPS I would not use for livestock, they’re just a bit too imprecise for my liking.