The best, without doubt, is the Busse Steel Heart E. About $300 though.
For a knife that is close to the Steel Heart performance without the extra cost, go for the Swap Rat Knives Camp Tramp. At just under $140 shipped to your house, it's an excellent buy.
The Steel Heart you can depend on with your life. The Camp Tramp seems to be nearly as indestructable.
For something cheaper, I hear good things about the BK&T CU7. It felt good in the hand, but the Busse and Swamp Rat lifetime unconditional guarantees make them the better value.
Striders are also very good, but are expensive as well.
Bottom line is: if you need a knife that you need to depend on without fail, get the Busse. Next in line is the Camp Tramp, then on to whatever else you might want. Although you might want to get one or two of the cheap ones, so you have something to back up to when they break.
Ed