FedEx usually beats UPS by a mile at domestic postage.
Things are complicated by the discounts offered to corporate shippers,
especially if they consolidate their shipments or co-locate at a
FedEx/UPS hub. But for the average schmoe, these are non-factors.
Up until a year or two ago I got 10% discounts on FedEx non-international
shipments because I had a corporate AmEx card, but I think this has either
been eliminated or scaled back to the point where it doesn't count.
If you're a small business and you want to ship via UPS, you have to
pay for the privilege of having an account and then more for a daily
pick-up.
Tim.