Sienna already looks much more balanced to me. I can't justify trying to critique her legs the way she's standing, but her topline is smooth and her neck is better, as is her dam's, though a little thick. What would you do with her?
I'm not sure what a CSH is but, I like Sienna better. she is built more uphill, longer neck, and a more lively/kind eye. you can definitely see the QH in the other horse (not that I don't like QH, I LOVE them) but she has more of a sad eye, built downhill and her neck seems too short for her body. what do you plan on doing with the foal? show or pleasure/trail ride? if you are planing on showing, I would pick #2 she would have more class in the show ring...if a trail horse, and you don't mind about conformation, I would pick #1 because she looks like she will be more laid backed. They both look sweet, good luck