The answer to this question is probably going to determine where you are going to spend the majority of the time in your role. If you say you like the agency side and don't really like it, they could hire you and give you mainly agency clients. Focus on answering what side you like and why you enjoy it.

Avoid saying that you love both, the interviewer knows that you don't truly like both. There has to be one that if you had to choose that you would prefer over the other. It's not a bad thing if you don't like working on one side over the other. Each business is different and they would rather put you in a position you love in order to retain you on their team.

"I prefer to work with agency clients because it allows me to strategize on a variety of different brands. I like expanding my mind and researching how different products impact culture. I enjoy learning how I can help understand who their ideal customer is and formulate a strategy to improve their branding."