Unique activities are almost certainly advantaged over common ones.
Well that's a different issue. All things being equal, passion for dungeons and dragons or firearms will put you at a disadvantage compared to passion for activities which aren't so stigmatized.
[Edit: The post below gives the impression that our conversations with admissions officers are our only reasons for believing the claims. We've also consulted with other sources such as How to Be a High School Superstar: A Revolutionary Plan to Get into College by Standing Out (Without Burning Out) which corroborate the admissions officers' remarks]
We spoke with admissions officers at Harvard, Yale, University of Chicago, Columbia, Stanford, MIT, Duke, University of Pennsylvania, Dartmouth, Williams, Johns Hopkins, Swarthmore, Brown, Northwestern and Caltech, about how they evaluate student participation in extracurricular activities, for 15 colleges total. Some things that we found based on college's statements are below.
Kawoomba suggests that colleges' statements on the first point below can't be taken at face value. What do you think?
Cross-posted from the Cognito Mentoring blog
See also High school extracurricular activities: factors to consider and College statements about extracurricular activities