My recent thinking on this has changed. I think the hatchet is the better tool, especially if you get a 3/4 cruisin' axe. And I just bought a couple of 15" Sandvik hatchets from A.M. Leonard.
See
www.amleo.com
These are great for putting in your trunk or the back of the pickup. Cost won't break you up. I can buy 5 or 10 of these or more for what you pay for some big camp knives.
But...I'm starting to lean towards the big campknife. The number one reason is that I think they are safer to use. Say you are chopping some small saplings to make a leanto. With a large blade, it's a lot easier to hit your mark. With the hatchet, swing short and you could futz up your leg or more important, critical parts of your body.
I've been using a hatchet since I was a kid and never had an accident but the big knife, I think, is still safer. I have a large, heavy duty Barteaux machete (a really old model with an aluminum handle) and it is quite a chopper. I've cleared a lot of brush and delimbed a lot of trees with it.
Right now I'm considering a RTAK. These seem like the best priced big knife out there for what you get. And I hate rubber-handled knives (no more for me) so the linen micarta handles on the RTAK appeal to me. I'm not worried in the least about the 1095 rusting. A little oxidation on a working knife doesn't mean squat.
Now, if you plan to do some serious chopping, get a full size axe or better (i.e. safer) still, get a saw.
For hiking, skip the big knife and hatchet unless you like to lug stuff around. Unless you are doing a "survival" hike, a small lightweight hunting knife like a Grohmann camper is all you need for most camp chores. The saw on an SAK will cut a lot of saplings but a nice Sandvik folding saw will really do a number and is fairly lightweight. This is my primary tool I use for clearing shooting lanes during hunting (you don't want to advertise your presence by doing a lot of chopping anyway). I haven't tried it but another nifty lightweight saw might be the Opinel.
http://www.marshmanbrothers.com/op2.jpg
I think the large Opinel folder would also make a great campknife!
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Hoodoo
The low, hoarse purr of the whirling stonethe light-pressd blade,
Diffusing, dropping, sideways-darting, in tiny showers of gold,
Sparkles from the wheel.
Walt Whitman