I thought the standard advice was to present as diverse a profile as possible.
This is hilarious. If the OP had asked "Should I major in Biology or Underwater Basket-weaving" everyone would be shouting "Do what you love!" (after the mandatory "Do a search" response of course). But when he asks whether he should do a BA or a BS, most people are saying "Don't be a *****!".
OP, this obviously depends on what the purpose of the BA/BS are. I got a BA in chemistry because, in my school, the BA was designed for people who were going to go into some professional field (Law, medicine, etc.) The difference was that for the BA you didn't have to take classes in spectroscopy, instrumental analysis, etc. In other word, you took all the "theory classes" but you didn't take any of the practical classes.
The reason I did this is because I wanted to take some non-science courses. I was able to take a fair amount of biology courses (anatomy, physiology, genetics, molecular biology). I minored in philosophy, and I took a couple of semesters of guitar.
Now that I am in medical school (I got accepted even with a "chem-lite" degree), the fact that I don't know how to operate a high pressure liquid chromatograph, or a physical properties measurement system, doesn't really matter. Had I gotten the BS, I would have taken an extra year of classes that would have had absolutely zero benefit for me.