What kind of traction do you need?
Turn over a shoe and take a peek at the outsole. The bigger and deeper the lugs, the better the shoe will grip on uneven or rocky and loose terrain. Conversely, shallower lugs provide more traction on flat trails. Let your typical hiking terrain guide you as you shop. Also consider the outsole’s texture: A softer sole is grippy but wears down faster than a harder sole (often found on heavier boots), while a harder sole provides less traction on slick surfaces.
Do you want more cushion or more protection?
The shoe’s midsole—the slice of material layered between the outsole and the upper—is where you’ll find a shoe’s cushion and underfoot protection. A highly cushioned midsole often uses EVA foam, which is comfortable (and often less expensive), but it breaks down more quickly. A stiffer midsole, which often uses polyurethane, will last longer and provide more protection from sharp rocks underfoot. Some boots have what’s called a rock plate, which is a hard piece of plastic (or metal, rarely) that adds stiffness and support for the roughest terrain.
Which material is best?
When comparing uppers (the part of the shoe that hugs your foot), the choice is largely weatherproofness and durability versus breathability and weight.
Synthetic uppers: If you’re plagued by sweaty feet—or plan to hike on mostly dry trails—synthetic uppers, especially with mesh, will keep your feet cooler (as long as they don’t have a waterproof liner). They’re also lighter weight, more affordable, and easier to break in, but these materials aren’t as durable as others.
Leather uppers: For the most durable option, opt for full-grain leather boots (full-grain leather uses the full thickness of the hide). Leather is naturally weather-resistant, but needs to be treated with special conditioners to perform at its best over time. Well-made and well-maintained leather boots can last for decades. Downside: Leather is less breathable, heavier, and takes longer to break in. Split-grain leather, like suede, strikes a middle-ground balance between durability and breathability.
Hybrids: Some shoes go for a best-of-both-worlds approach, with a mix of synthetic and leather.