Ka-Bar makes a couple fine folders. The Mule is a large solid folder that is pretty durable and functional. The Dozer is not as big but still quite ergonomic and useful. I have the Mule and for the money (less than $50) it is a great deal for a reliable folding knife.

Depending on perspective, the ultimate knife is either the one I have on hand at the time I really need a knife, or else it is the one I always wish I had with me but never seem to. Funny paradox that.