This one. I can't even remember her name, that's how much I didn't like her. I don't remember most of the episodes she was in and what I do remember I only enjoy because The Doctor was just so freaking fantastic. She was a well written character who just wasn't brought to life properly by the actress, I think. From what I remember, her time with the doctor was muted, mostly punctuated by fear, and actually kind of annoying. Her last episode fit the character fairly well, her deciding to be part of a military operation, but all in all I was incredibly unimpressed.
To be fair, I also slept through many of her episodes.