西语 is the best choice and it is easy and the most useful one for

西语 is the best choice and it is easy and the most useful one for college. If your child can finish 3 years in high school, they don't have to take foreign language classes in college, which is required for a college degree. Latin is only useful for if you want to do a major related to that. French is not very commonly offered in high schools thus not a good choice.

Chinese won't stick since they have little chance to really use it.