Hi Tara.
It depends on exactly where, and to what end. The best tool for hammering nails is a hammer. Not all problems, though, are nails.
I think in the abstract, alone-in-the-woods thought experiment, a heavy-bladed knife or hatchet would be the single most useful tool, as you can fashion most of what else you need from
wood, in terms of survival.
I mean, a drill would be great, unless that was all you had, in which case it's a poor substitute for a wood-shaping tool, or even an axe or hatchet.
As an interesting observation, I have found that in a garden establishment setting, where I was working by hand, the most effort-saving, productivity-enhancing tool I had to augment digging (in this case, my first hugelbeet, which started with an excavated trench about 18' long, five wide and three deep) was that As-Seen-On-TV Garden Claw device, or one like it, with corkscrew tines allowing one to loosen about four to six inches of all but the hardest-packed hardpan.
Your specific heavy equipment needs depend on what you want to do. Some of the members on this site log their properties rotationally or convert them to more intensive production. It makes sense for them to have skidders, for instance.
But even if you intend to put serious
earthworks in, firstly that's more a one-time than an ongoing thing, so it would be worth looking into things like how often after initial projects you would be using it, or what the retained value might be for resale, and what the comparable cost of rental would be,
should that be an option for you.
This is a great question. People, I find, like panaceas, golden-bullet solutions. Those only exist where you shrink the focus of the system being studied to such an extent that you can externalise undesired byproducts. It's a good conversation to have.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein