I find it interesting, but not surprising, how most of these answers have selected "a person who loves you."

This choice supports what is known in sociology as the principle of least interest. The principle states that the person who is least invested in the intimate relationship has the most power. This is because the person who wants the relationship will be more willing to make compromises and sacrifices to keep the relationship going. Least interested or most indifferent=most powerful.

Several answerers have explained their choice by saying that they could grow to love the person they're with. This also has to do with power in a relationship. You want your feelings to develop on your own terms, within your own control. Like Anurup Datta said in his answer, someone on the other side of the fence would be tormented by doubts about his/her partner's feelings (or lack of feelings).

Being in a relationship with someone you love when they do not love you is a very vulnerable position and will only lead to pain. Therefore, I would choose to be with someone who loves me even if I don't love them. It may not be the most honorable choice, but it is a human one.

P.S. This makes me think of this song: