Old thread but I thought I'd still add my experience because I see boot sizing is year in and year out a hot topic of conversation everywhere.
Right foot = 11 3/8" long, 4 1/2" wide, 8" arch length
Left foot = 11 5/8" long, 4 3/16" wide, 8 1/8 arch length
Right foot is a 12 EE via brannock device/measurements
Left foot is a 13 C via brannock device/measurements
I have been wearing a 12 wide mountain extreme 400 for 9 years. Super comfortable, some heel slip but never a blister. So there is that. But, I feel like all the width is just over the top "sloppy, imprecise, clod hopping". I've never liked that about them. Strong and warm and no blisters, so I go with it.
I recently got Desert Guide Hikers in 12medium and length is fine, toe box is just a little tight on pinky toe, and balls of feet are a little tight, but precision of steps and heel hold is awesome. Nonetheless I just sent them in to Kenetrek to have the forefoot stretched. I suspect this will make them perfect. We'll see.
I also recently picked up some Bridger High boots and in a 13 medium they are as perfect as can be. Nothing is ever totally perfect because of the difference in foot sizes, but dang these are close.