I've gone to Nags Head for at least a week every summer for the past 34 years, so I am a little biased but I've also stayed in Duck and places south of Manteo as well.

Keep in mind I have a very pro Nags Head bias, but my super simple breakdown would be:

Duck - too yuppyish/congested
Towns south of Manteo - too remote/isolated
Nags Head - just right