"Skeptic" is also implicitly positive. A skeptic wants to know truth. A skeptic lives as though one is on a journey - a pilgrimage for some - towards a better understanding of the cosmos and ourselves.
Of all the labels used by the atheist/agnostic/freethinker/skeptic community, I am convinced skeptic is the most important. Some disagree with me, and their reasons are worth consideration. Chief among them (in my mind) is that a label like "atheist" still carries negative (and I mean "negative" in the colloquial sense of being bad) connotations which fuel prejudice and misconceptions about what kind of people atheists are, and the more open and expressive we are with the label, the better our chances of convincing more people that we're not baby-eaters or devoid of morality or followers of the Dark Lord.
While many atheists became such because they were first skeptics, one can be an atheist and not a skeptic. They are not synonymous. Likewise, one can be a Christian and be a skeptic, simply because skeptics can actually disagree with each other. The day every person in the world who identifies as a "skeptic" agrees about everything is the day we've likely lost any semblance of being skeptics.
Granted, the nature of having faith makes being a skeptic more difficult. This was exemplified in the debate held back in February between Bill Nye and Ken Ham when each was asked: "What, if anything, would ever change your mind?" Ken Ham's answer was "Nothing," whereas Bill Nye's response was "Just one piece of evidence."
The soul of skepticism is the willingness to change one's mind when presented with a good reason to do so. the foundation of faith is the acceptance of certain tenets and beliefs and reliance upon their veracity independent of whether there is evidence for or against those tenets.
The reason I say that "skeptic" is the most important label we can use is because our skepticism is what has propelled us towards further advancements in science, technology, and medicine, and given us the knowledge and understanding of the world we currently have. It's the pursuit of truth, not the conformity to comfort, that will truly satisfy our instinctive curiosity, help us find fulfillment, and give us hope for the future.