I lived out of town and learned at Ner Israel for five years. I did my best learning after I left.
I agree with Tzippi. I’ve seen many good boys go bad when going away to an out of town Yeshiva; it’s not home and there can be no substitute for family life in terms of turning out normal. If you are a future gadole hador, maybe; but that’s not going to happen in most American yeshivas anymore.
Most of the best bachrim I see today are living at home through high school and beyond. Ner Israel, Telshe, etc. filled a need when there were few other yeshivas, today that’s changed and there is considerable talent elsewhere.