Q: How do I choose?
A: The choice between whether to follow the BAH or BSCH depends upon your interests, abilities and career plans. Choosing a BSCH degree usually means that you are interested in and able to successfully complete first year science courses which, in some cases, require Grade 12 prerequisite courses: http://www.queensu.ca/admission/apply/firstyear/requirements/Program/artsci/science.html
Psychology graduate programs rarely distinguish between the BAH and BSCH; both qualify students for admission to graduate programs in research and counseling. More important for graduate admissions is your specific coursework and research experience. If you are applying for Neuroscience, have you taken Brain and Behaviour and some science courses? For Clinical, have you taken Abnormal, Personality or Developmental Psychology? And for most programs, having worked in a research lab, completed a 570/3.0 or 575/3.0 Directed Special lab course and/or done your thesis makes you the most competitive.