Most important is to be academically prepared once into the private HS, the testing (SSAT) not exactly at a high level, and doesn't assess writing, so really important to choose a school (for HS and for life in general) that will give the best academic preparation for success in terms of math skills, writing, vocabulary. Talk to prior parents that had kids at each of these schools who went onto top privates and find out whether they were well-prepared.