There are SOOO many High Schools in America, I don't think you could necessarily rate them by best 'academically' minus the specialty schools: Magnet schools, Ivy League/Higher Up 'Prep' Schools, Art Academies, etc. I mean, there are certain boarding private schools that are considered to be 'top notch,' but it depends on who you talk to
Being in CT, we've got a LOT of swanky, fancy-schmancy prep schools (Choate, Kingswood-Oxford, Avon-Old Farms, Miss Porter's, etc), some who even have international boarding students.
As for cheerleading in HS, another issue is the out-of-state traveling rules for HS sports (why Georgia teams can't compete at NCA/UCA) and varying 'state competition rules', meaning each state's competition emphasizes different things and even RUNS differently. Most of the best schools, however, DO compete NCA/UCA, so if you watch their HS nationals you can get a decent idea.
I remember being in Ireland and my friends telling me they went to college and I got so confused..until I realized they meant it more like HS than American 'college'.