I know that Dance Passion produces a pretty good number of very good junior/youth couples, so it is definitely a good place.
another studio to check out is Kings Dancesport, located near kings highway Q train station. This is one of the most established kids studios.
Main latin coach there is Roman Nabatov, and other teachers they hire are always good (i know a lot of teachers and former teachers there).
there are plenty of other kids studios in Brooklyn, and i think most of them are good and have good environment. the bigger ones are all good. so you might as well try the most convinient one. In the future it is quite possible your daughter would switch studios (even maybe more than once) due to a partner being from a different studio.. but that's probably a while from now, and also there is nothign wrong with that.