If we are looking at brain effects, the advantages must outweigh the risk of brain injury inherent to the activity. Playing football might help brain plasticity but at considerable risk of brain injuries. Most all the team sports (soccer, lacrosse, hockey etc) have varying degrees of associated brain injury risks, but not dance or other non-competitive sports. At lease when dance (or rock climbing) is competitive the competitors do not share a movement space and so don't knock heads.