PhD programs in Quant Marketing tend to be top heavy, that is most of the schools that have large(r) quant marketing programs tend to be the top schools. Also as part of the business school, the funding for quant marketing tends to be quite generous (compared to other disciplines). Career wise in academia, quant marketing gets paid the highest on average (check out the who went where surveys on docsig DocSIG - Who Went Where and Salary Surveys) compared to the other 2 marketing disciplines (CB, strategy). In terms of competitiveness to get in... well like anything else the top schools will be difficult to get in. Also marketing PhD programs tend to accept only a few students per year (the top schools will take around 5, the lower ranked schools maybe 1-2), so that will boost up competitiveness of admissions. Plus people going into Quant Marketing will not only come from Economics but also Engineering, and other Quant-related fields.