Case, Sodbusters and Yeller Handles for price paid might be the hardest working folding knives around.
Buck, while I don't like everything they make most are well worth the price paid and everyone should own a 110.
Boker, their traditional folders are just great plain ol'pocket knifes.
Rat, for the price you get a lot of knife with them.
Bark River, with their plain jane models there is a ton of bang for the $.
Kabar, GI model military knife of the free world since WWII.
Spyderco, sure they can look funky to a geezer like me but a hard working knife none the less.
Leatherman, sure they're just not knives but they can be useful little devils to have on you.