I saved her because time and time again she has helped Lee. Take for example when she stuck her neck out for him when they first met, and brought him into the drugstore, or how when she went with him to save Glen, all Doug basically did was reprogram a remote for him. I have to admit having a tech savvy person around would probably be pretty helpful, considering it is much easier to learn to shoot a weapon than learn tech skills in a zombie apocalypse, but I tried to look at it from Lee's perspective as to which he would probably feel closer to.
I tried to do for people based on their usefulness as a whole, take for example Duck, he is a child, and isn't really going to be much help as far as anything goes, I was willing to let him die over Shawn, and was willing to let him get thrown out when it was thought he had been bitten. I realize it probably sounds cold, but you have to put things into perspective, yes this person may be a child, or tech savvy, or whatever, but how is that going to be useful to you and the rest of the group as a whole in the future.