Be honest and let the interviewer know which one you prefer and why. Do not speak negatively about the other option though. Speak positively about both options.

"I like working with people, which is why I chose to pursue a career in HR. I enjoy the social aspect and like to help people. Having said that, it can also be relaxing to sit in front of a computer and focus on one task at a time. I do well with both people and computers, but if I had to choose one, I'd choose people."