surfer mentioned R’ Alster’s yeshiva. I go to his shul in Bklyn, i know firsthand that the students there are top-rate, really fine boys-and R’ Alster himself is worth going to the yeshiva for!
also, kollelwife asked about a few schools including Peekskill and South Fallsburg……..one of my brothers just finished BM in Peekskill. Happens to be the yeshiva wasnt his type at all, but he loved it–the R’Y is very into the boys and takes a sincere interest in their learning and growth process
S. Fallsburg: my father went there, and he raised me…lol jk dont know that much about it, but I think it has a very good reputation…good luck!