If I had to pick only one, I would have to go with independence. Several other traits (range, hunting drive) are often the result of a dog being very independent. Might not make the best dog in the world, but a dog that will at the very least get deep and look around will usually make somewhat of a fair dog. It's also a trait that can begin to be evaluated in pups at a very young age and often times can tell you what to expect of a dog later in life. I believe it to be often overlooked in a lot of today's breedings, and I also believe it to be one of the traits that can be negatively influenced early by improper handling.
I agree with a lot of what Bryant is saying here...a certain amount of independence is needed but not to the point that the dog won't honor a bay or pack up. Most of the hunting traits can be tested for in certain breeds when they are pups...and the right handling will bring out the best in what is already in the pup...
