No question, boots are a hiker's most critical gear. The right pair will help you glide down the trail with a smile on your face, while poor-quality boots will have you gritting your teeth with every footfall.
When it comes to selecting the shoe for you, forget about looks, numerical sizes, flashy features, or even what your friends recommend--unless their feet are identical to yours. The issues you should consider are comfort, durability, stability, weight, warmth, and water resistance.
The most important thing in buying boots is to get a good fit, with a snug fit at the heel and wiggling room for your toes in front. A knowledgeable bootfitter can help with fit.
MAKING SENSE OF STYLES
Select your boots based on the terrain you will hike on and the loads you expect to carry. However, because added ounces and pounds on your feet really take their toll in terms of energy expenditure by the end of the day, go for the lightest boots you can get away with. For instance, a pair of off-trail boots would be overkill for a backpacker who does weekend trips with a light pack and sticks primarily to trails. Here's a primer on selecting styles.
Trail. When your pack is light and the trail well kept, these low-cut or midcut boots are the best choice. Their combination of fabric/ leather or split-leather construction usually has multiple seams, so unless a waterproof/breathable liner is hiding inside, you'll need to augment them with Gore-Tex socks or an application of waterproofing. Trail shoes have stiffer soles, more stability, and better traction than typical running or walking shoes, but most people will find them too unstable under a big payload on slippery or rocky terrain. Consider using low-cut ankle gaiters to keep out trail detritus.
Rough-trail. If light backpacking or aggressive dayhiking is your thing, then these ankle-high boots are your best bet. Made from fabric/leather combinations or split-grain leather, some have waterproof/breathable liners, while others are porous and well ventilated for hot desert conditions. Tapered plastic midsoles or half-length shanks give these boots enough sole rigidity to armor your feet against stony trails, yet still allow good flex at the balls of the feet. Some strong-footed hikers prefer these lightweight boots for extended backpacking through serious outback; for the rest of us, when the going gets rough, it's time to trade up.
Off-trail. When the only trail you can find is a goat path through talus and alder tangles, you'll appreciate the full-grain leather, above-ankle support, and rigid sole stability that off-trail boots provide. The core boot choice for long backpack trips under heavy loads, these boots offer plenty of protection for your feet, yet flex enough at the balls of your feet for the shorter stride length dictated by tough terrain and a weighty pack. High-mileage hikers will eventually pummel off-trail boots into surprising softness, but expect a lengthy break-in time until the sole and heel cup soften. Off-trail boots offer superior waterproofing and durability due to their all-leather construction and minimal seams. Many off-trail boots are surprisingly lightweight, thanks to newer midsole/sole constructions. Some models have a lip on the welt of the sole to accept certain types of crampons for glacier travel or the new generation of snowshoe bindings.
Mountaineering.These boots are characterized by full-grain leather uppers, minimal seams, excellent traction, and sometimes a bit of insulation. They rise well above the ankle and accept crampons. With full-length shanks or stiff nylon midsoles, mountaineering boots are usually too rigid for comfortable full-stride hiking. Still, under a heavy pack on steep terrain, your stride will be shorter anyway, and they'll get you to the peak. Make sure these boots are well broken in before attempting much mileage, or you'll get world-record blisters. Look for rockered soles, minimal heel slippage, and rubber rands along the welt for durability and waterproofing.
Technical-scrambling.These are primarily low-cut and midheight hybrids with a close fit, sticky rubber soles, and anti-abrasion toe rands. Designed for light hiking and scrambling, they'll suffice under a lightweight backpack, given good trail conditions. If you plan to use them for serious trail travel, you'll want gaiters to keep out gravel, sand, and twigs.