half ton truck and a quad or side by side, maybe a dirt bike. Seriously, I’ve been all over the national forests in eastern WA, north Idaho, and west Montana in both a 1500 regular cab silverado with a truetrac and open front diff and a two door Rubicon, and I never went anywhere with the Rubicon that I couldn’t have gone with the Silverado. You’re limited as much by the physical size of the vehicle as anything. If a road is open for passenger vehicles, any 4x4 will do it. Otherwise, it will be a hiking or ATV trail only.
Any full frame 4x4 with e-rated tires, a tow strap, tire chains, and a chainsaw is my recommendation. Winches are nice but really the forest roads are maintained well enough you will never need one. A chainsaw and tow strap will save your butt when a tree gets blown down over the road, though.
All this assumes you’re going exploring and not just wanting to go to the off-road park to drive over obstacles. That’s a whole different deal, and I can’t see why anybody would take a new vehicle to do that sort of thing. But maybe that’s what you have in mind?
Have fun, be careful, if you go exploring by yourself, take an emergency beacon.