Choosing Materials Science vs. BME PhD-- Job prospects?

[chemgirl2013]

Hoping to get some advice from people in the field! I am not an engineer (undergrad was in Chemistry); so, my background is in synthetic organic chemistry (specifically, polymers), and my research interest is in the area of biomaterials. I have been accepted to some great top 10 programs in both Biomedical Engineering and Materials Science, so there is no question that any of my programs' reputations is enough to pick one over other. My question is more long-term-- which field has better job prospects (industry options, flexibility of industry)? I know that money isn't everything, but which has better income potential? My current advisor says to go with Materials Science as she did her PhD in Chem E and is currently a BME prof. She says its more established historically. If MSE is the better option, should I give up biomaterials work altogether  and work in an area more lucrative, like energy? From my perspective, because I currently work in a BME lab, BME seems to be pretty vague and sort of an umbrella of various backgrounds (Bio, MechE, EE, Chem) that sometimes lacks a clear focus. But I enjoy the interdisciplinary nature of the field. I'm just wondering if for this reason doing BME for a PhD will hurt me long-term. Thoughts? Especially people doing PhDs in BME or MSE?