Take a position: Marketing research should be quantitative versus marketing research should be qualitative.
Many marketing researchers have their favorite research approaches or techniques, although different researchers often have different preferences. Some researchers maintain that the only way to really learn about consumers or brands is through indepth, qualitative research. Others contend that the only legitimate and defensible form of marketing research involves quantitative measures.
In the real world, I would argue that both approaches have a place. However, since this question calls for one position, I will argue that qualitative research is more important.
The reason for this is that consumers' relationships with the things that they buy can be too complicated to reduce to numbers. People may have complex reasons for why they prefer a give product. If marketing researchers fail to uncover the true nature of these reasons, they may change the product in ways that will end up driving away customers. Because decisions about what product to buy are made for complex and personal reasons, it is better to do qualitative research that can capture that complexity and give the producer a better idea of what drives sales.