The most extreme conditions?? There is NOTHING in a dealership that will take on the most extreme conditions out there and live to tell the tale. Even a Rubicon needs bigger tires and more ground clearance, not to mention a winch. And a Raptor? An impressive and capable vehicle but far from being a practical off-roader.
Not so sure about that... ever been to a Mog dealer? You can buy one of those trucks off the lot that could run the road of bones.
Now... as far as vehicles that are in the realm of reasonably affordable for a workin' stiff...
Rubicons are kewl, as they come with locking diffs. They are not well protected, however, and have some goofy stuff, like a low hanging alternator that does not like to get wet, a front pumpkin that likes to hit rocks, and no protection for the steering components. This combined with the low clearance in its stock configuration says... jack it up first!
The most capable vehicle that you COULD buy... and by that I mean one that will not only get you out there, but get you back as well... out of the box that I know of would be a toss up between the factory locked 1st gen Tacomas and the 3rd gen 4runners. The long wheelbase of the Tacos exudes incredible climbing ability and stability. The more compact 4runners are better on the twisty, bumpy stuff. Available on both models were oversize tire options (31.5-ish). The lack of diff lockers in the front is the only drawback, but I would trade this for the additional protection any day of the week.
Raptors are also kewl, but suffer from Ford's age old problems... power steering sucks and the alternators fry themselves regularly.
All in all... I say the most capable vehicle is the one that doesn't break when abused... so my vote is for Toyota's bullet proof reliability.
I'm rambling... go get yourself a 2010 4runner trail edition, and complete the Rubicon Trail bone stock. BTW, have you ever driven one of the new land cruisers?... the traction control system on the 200 series will soon be legendary.