Respectfully, the description above does not align with our family’s experience at Episcopal. My daughter turned down Middlesex to attend Episcopal, and while she has good grades, the academics are not “very relaxed”. She has to work hard to do well, but not to an unhealthy stress level. She intentionally chose EHS because it had the right (for her) mix of excellent academics, extracurriculars, and culture of healthy balance.
I think the OP has three good choices, and can’t go wrong with any of them!