This might sound a little sadistic, but the main reason the sold-by-her-parents-option appeals to me the most is the potential for turmoil; it's the inner turmoil that makes Jack so real, the fact that Jack feels. Couple that with the gaping holes in her past, and she just
creates interest. If one of those holes should be filled, it would fit the character if it created some conflict. Jack's a growing character after all, and all her developments come out of this stuff bubbling just under her surface.
I like the idea of Shep's treatment of her potentially changing the outcome of the encounter, and there's a chance here for one of the least well-rounded characters to get some development in their character - Shepard. What if a Shep that has romanced Jack goes with her on this little journey, they find out the rather sad truth, and Shepard loses it? I know if I took my lover to hunt down their long lost parents and the truth is they casually, needlessly sold her and there wasn't a shred of guilt or remorse... well, someone would be getting force-fed my Carnifex. If Jack then becomes the voice of reason in that situation...
Man, am I gonna have to write
that one eventually

Ok, part of me (the sentimental part) would like Jack to find someone other than Shepard that would care about her, but an event that makes her realise the crew of the Normandy is as real and caring a family as any would be just as sweet. Don't get me wrong, I feel for our girl, but I think it's out of these moments of doubt, fear, anger, strength, sorrow and humanity that Jack displays that have made her come to life for so many of us. If Jack's past was to be truly explored, it would be all the richer for some pathos as opposed to some sugardusting of schmaltz.