My experience, both in Wyoming and Nevada, is that FedEx subcontracts out so much of their delivery to the USPS as to be a scam and a hazard. Sometimes, I get deliveries of firearms via FedEx, and when that's subbed out via the USPS, it can result in uncomfortable conversations with the local postmaster - but it isn't my fault, because whoever sent the firearm (or other prohibited items) to me didn't know at their end that FexEx was going to drop the package into the USPS for the final routing. I've had this issue both in Nevada and here in Wyoming.

UPS has a better developed rural route system, but at times you're at the mercy of unionized drivers who violate UPS rules and don't care because they know they're difficult to fire.  When you have a UPS driver in a rural area that knows what they're doing (and I have), UPS wins, hands down.