If your kids are going to be going to private school, a lot of the "normal rankings" for suburbs will be flawed. Towns with good schools (Medfield, Belmont, Lexington, Sharon, etc.) also tend to have extremely expensive housing markets and high property tax rates.

With private school, my advice would be to find a town next to one of the top towns but with more affordable housing costs (e.g. Canton).

If you decide to send your kids to public school, it's really as simple as finding the best school district within reasonable commuting distance which you can afford. The towns with good schools are pretty much uniformly very nice places to live.