From a health perspective, which nutrient category is the most important to obtain in a primal/paleo manner? In other words, is it most important to eat paleo carbs, paleo fats or paleo proteins?

Not that I think a choice needs to be made, but from an academic perspective, if you were only going to make one change from the SAD, which improvement would yield the most gains?

My sense, from the limited reading I have done, is that cleaning up the carb sources is most important. Curious about other opinions (or if there is a difinitive answer).