I thought I prefered Laura, but now I'd be happy with either of the remaining girls. Ashley's eyes are so big and emotive that she seems a little "scared and unsure" in the same way that the Sandy character is. She seems to be putting a little more into the acting and is a better dancer. Laura is the better vocalist and excels in the dancing and acting parts as well, but there is something about her that is so polished and put together that she doesn't come across as vulnerable in the way that Ashley does.
I think both girls could do a great job.