Short answer- FedEx
Longer answer-
Today I needed to ship one of my basses to a luthier a few states away for some neck work. I packed it in a cardboard box not much bigger than the case itself. I first brought the box to The UPS Store and was quoted $21.00 for ground (7-10day) + insurance. This seemed reasonable enough. After they started the transaction (took my name, phone #, address, blah blah) a different employee came over and took over the process. He re-measured the box and mysteriously came up with a new quote of $33.

Apparently the previous employee (who was indeed the manager of the store) didn't enter the box as "oversize". Here's the kicker- I told them I also needed insurance for $2900 and that brought my total to $91.12, with the package arriving in 7-10days. Bait and switch or not, needless to say I was out of there.
Brought the package to FedEx and was charged a measley $29.02 for 2 day shipping including insurance for $2900.
UPS= hassles + slower ship time + 3X the cost.
FedEx is getting all of my business from now on.