You might want to check out Doug's recommendations for fixed blades and folders. I don't think you'd go wrong with one from each list.

Personally, my heaviest duty fixed blade is a Swamp Rat Howling Rat, and I'd feel pretty happy having that with me anywhere. It's not huge and it's sort of ugly, but it's got an extremely useful shape, is very sharp and feels very good in the hand. From what I hear and read, the Swamp Rat knives are darn near indestructible. To tell the truth, though, I rarely carry a fixed blade.

I do carry a folder of around 3" every day, though, and three of my favorites are the KaBar Dozier folding hunter, Doug's RSK MK1 mini, and a Bradley Alias II.