Well, simply "hiking" is one of those activities that generally doesn't require the cutting of anything at all. But I do think everyone should carry a basic blade, after all "knife" is one of the Ten Essentials.
If you said a little more about your hiking adventures it would be easier to recommend a particular knife style and size. Do you hunt or fish when hiking? Do you car camp and need a large blade for splitting wood for the campfire? Long-distance backpacking? Food prep? Chopping wood for winter camping? Or just want a small blade to have in your pocket?
I've lived and worked outdoors for years, and still frequently dayhike and travel in a wide variety of conditions. Deserts, canyons, rain forests, alpine mountains...
Working in the Philmont backcountry for ten years and encountering thousands of backpackers, I feel confident in saying that more hikers and backpackers carry a Swiss Army Knife than any other single piece of gear.
During a career a professional archaeologist I hiked all day long, for weeks or months at a time, for twelve years. The #8 Opinel was my standard carry during that time. It easily performed every cutting task ever encountered.
I've moved on from the Opinel now, preferring a fixed blade for safety and hygiene. My first choice, the AG Russell Hunters Scalpel. Can't rave about this knife enough. HUGE Thumbs Up. :thumbup:
Believe it or not, even with 500+ knives in my collection, including Spyderco, Benchmade, customs, Becker, KaBar, Gerber, Buck, SAK...
this is my first choice every time I head to the woods.