Truthfully, the difference between the BA and the BS will not matter one iota.
Not a single Pharmacy school is going to care about whether your degree is from the College of Letters and Science or whether it's a BS from the College of Biological Sciences - What's going to matter is your scores on the pre-requisites, like Calculus, Physics, Chemistry (Physical and Organic), Biology and more. Just as there are these tougher pre-requisites there are also other ones, such as History, Public Speaking, and English, which are in the "domain" of a BA. But you don't see any preference given to one degree or the other.
Much like law, you'll have students with degrees in all sorts of disciplines, from theater, to psychology, sociology and so on. Now, some degrees, like a UG major in biochemistry, will expose you much more to the "hard sciences" than would a UG course of study in, say, Psychology (What I happened to get my BA in). In THAT respect, a BS would be to your advantage.
But really, and I know everyone else has taken a round-about way of saying this, you need to go with what you're comfortable with. As long as your science GPA reflects an interest in what you're learning (and comprehension thereof), you can get a BA in Basket Weaving and I do believe even UCSF will consider your application. Consider the following data:
Majors
Top 2 majors: biology and biochemistry.
Non-traditional majors: accounting, anthropology, architecture, art history, biotechnology, business, english, environmental studies, law, literature, mathematics, music, philosophy, political science, sociology, theatre/cinema.
You can plainly see, from UCSF's own website, that whether it's a BS or a BA, what matters is this,
Breadth of coursework
Attendance at a 4-year college
More than 190 quarter units of completed college coursework
Completion of a bachelor of science or bachelor of arts degree
A cumulative grade point average of 3.63
A grade point average in prepharmacy requirements of 3.56
That should quell your inner turmoil.
Source:
http://pharmacy.ucsf.edu/pharmd/admissions/aboutstudents/