An aggregation of experiences (subjective), but also actual objective info. Does the school have a sport your kid wants to play? How are the coaches of that sport and have they had success? Does it have a club your kid wants to participate in? How active is the PTA? Does the school host community outreach events? Does it have a specific honors program? Does it offer a foreign language you want your kid to take?

Ask any teacher and they will tell you greatschools rankings should never be the deciding factor of a school.

My kid’s school is a 7/10. Greatschools shows it as lower than a neighboring school (9/10) due to inequality of scores, even though it’s well known in the community that our school is top notch, if not better. Our school has a 15% Hispanic population and many of those kids speak English as a 2nd language. Their test scores are lower than the non-Hispanic kids, and greatschools flags that as inequality. (Even though the primary English speaking kids score in the top 10% in the state).

All I’m saying is you need to peel the onion back a little and dig. Don’t rely on a single website to make a decision for you.