I love her. She's cool and has a nice personality. Christine Chapel would be my second choice. I love her too :-)

I know she was only there for the "space seed" episode, but I really liked her character. :)

@SherlockStark
I know what you mean. I liked her too. As Khan said she's dead I was crying a little bit.

Uhura of course

Christine Chapel provided nothing useful to the crew or to any of the storylines in the episodes or in the films.

Marla McGivers was a dumb weak incompetent female. In Space Seed, she knows or should know that Khan has a violent history and showed no remorse for it, he not only physical abuses her, he threatens to kill Kirk, the crew, has one of his men hit Uhura... and yet Marla still wanted to be with him... yeah, what great character she was...

The rest are just ok.

Yes, Marla was dumb, but I liked her, I don't know why.
But Christine: There was one episode: What are Little Girls Made of?
Without christine this episode couldn't exist.

@VINiman: I agree that Khan and Marla's relationship started in an unhealthy relationship, but that relationship evolved into an everlasting true love relationship (just read the books such as "to rein in hell"). As for her being dumb, I don't think it was if you put yourself in her shoes. She was a competent and knowledgeable woman in her own field (history) yet she was treated as if she was a useless crew member. Suddenly, along comes a man that appreciates her knowledge and interests and even appreciates her beauty. What would you do in that case? Would you not "fall for" Khan if you were her?