If Amazon doesn't deliver on time...they'll give an extra month of prime for free...but you can push for them to give you credit. I once got $25 credit. Also FEDEX may have the nicest tracking but out of all the shipping comp. (DHL, UPS, USPS, FEDEX)
A study by consumer reports where they shipped packages with sensors (detect temp, drop length) found that Fedex was the worst w/ dropping packages at a pretty high height...and USPS won w/ the best care of packages.
Will search for source if you guys insist.