If it is packaged appropriately, it don't really matter.
Fed ex ground has the "It might get there in 1-3 days". You can always track it though and get the exact time it will arrive.
UPS is more consistent with the "If you ship from point A to point B, it will take exactly 2 days"
I would say just go with what you want to pay for, or not pay for, what ever the case may be.
I will tell you personally as someone who works for a company that ships hundreds, and some days even thousands of packages, we loath Fed Ex.
UPS for domestic and Canada just way out services Fed Ex, it is a simple matter of missing, destroyed and late delivery. UPS wins this war hands down.
UPS picks up later in the day, which is uber important for a business that ships the number of time sensitive packages we do.
Fed Ex is a little better for overseas.
But this is just my opinion for business purposes. For home delivery, it's probably a toss up.