Noah, remember with a border collie that they need CONSTANT stimulation. Same goes for aussies. This means that your mom would have to be working with the dog while you are at school.
If she has been iffy about it thus far, it is best to go with the breed SHE likes (or the closest ones to it). And definitely better to go for one who won't need her to be working with him/her during your school day.
Mom To~ Dakoda (b/t GSD), Acheron (black GSD)