people are emotionally attached, and i think that clouds their judgement on cars. also, theres this compulsion to be "right" that clouds everyday judgement. dont get me wrong, i love cool and unusual ****, and i may get attached to a particular car, but not a brand in general.
that having been said, i read the question as "best sold in the US, FOR the US"
that means road conditions and vehicular needs must be taken int account.
so, off the bat, unimog size stuff is mostly useless. there are LEGAL roads in new england, that are as tough as moab, and worse in the spring, that something that big wont fit on, period.
diesel? who cares. unless you tow 13,000 pounds everyday, its in your head. fuel is cheap in the US, and gas stations abound.
average track and tire size... now thats a big one. what was great 20 years ago doesnt work now. so, you have to take period in consideration. those tires on a first gen 4 runner arnt gonna cut it when you see excursions on 37's digging their way up the hill. better get set to drag it. not to mention, one 30" tire in a rut and the other on the crown all day, blech. old jeeps and 40's are a bit narrow but workable. sammies are just too small.
overland in the US includes lots of highways and dry dirt roads too. outside of wheeling "trails" like the rubicon you have to ask if SFA is worth the trade off for the comfort and washboard handling of IFS. yea, i know, solid is more durable... not really. thats a general statement that compares apples to oranges. a properly designed IFS is as durable as a tube. sure, there are 4 CV's, but, a toyota shaft lasts 200,000 miles with 35's and no maintenance, whereas a G will eat bearing for lunch. i'll take a yota minitruck IFS over a dana 30 jeep anyday. in the end, durability and reliability is in the design criteria.
for those reasons, the best sold in the US can be picked from shorter wheelbase modern pickups, and SUV's.
having owned and wheeled lots of live axle trucks and suv's, (f-series, defender, landcruisers, G) and if one is to differentiate overland travel from wheeling, i think the size, shape, modability, durability, reliability, comfort, capability, payload, all point to a 100 landcruiser.
now, if you want to think international in a US sourced rig, to me its not that much different. south africa doesnt need 33's, and in siberia, the dude in a unimog is your best friend. but if i really wanted to keep all my road options available worldwide, i'd still stick to a 100.