The most common definition of anarchy is the absence or failure of government, resulting in a state of chaos, confusion and disorder, so unless one is addressing libertarians who are familiar with the non-aggression principle, it's important to be clear that anarchism is based on the idea of voluntary, non-monopolistic, competitive governments. The purest expression of this idea, one that is also intuitively understandable to people who are not well versed in abstract concepts, is "voluntary government", which should be contrasted with the State which represents the principle of "aggressive government". Self government is too confusing, as it gives the impression that it only applies to individuals, not organized groups.
I vote for "voluntary government".