I agree with @Altras and @Publisher. Most of the answers to these questions depend on the student, not the school.
- Intensity of the competition among the students - is it healthy or toxic?
I doubt anyone will say that anything about their BS is toxic. How a student responds to perceived competition can be healthy or not, but that is a personal decision. In all my time here, I’ve never read any genuine post that says students at their school are anything but collaborative–no matter what the outside perception might be. For example, anytime someone posts that they’ve heard that Exeter and Choate are cutthroat, within minutes, someone will debunk that from their experience. I would say that Choate is collaboratively competitive in a very healthy way.
- Amount of homework - let’s say hours per day, so that I can compare apples-to-apples
Most boarding schools say they give about 40 minutes of homework per class, so approximately 3 hours/night, but how long that actually takes depends on how organized and focused the student is.
- Academics/fun balance
Again, depends on the student. Any student can make school a grind, but none of the schools are set up to be that way, and most students are able to find a healthy balance. In general, BS students work hard and play hard.
- Amount of stress experienced by students.
Ditto. Depends on the how the student deals with demands. Stress is not something a school places on a student. Stress is your body’s reaction to a challenge or demand, so only you know how you respond to and deal with stress. Boarding school will give you plenty of outlets for blowing off steam and plenty of support if you feel overwhelmed.
- Quality of food
Edible at all schools, some better than others, but I’ve never read any post claiming that the food at their school is abysmal. Choate’s was very good. NMH’s was better. You’ll have multiple dining options at every school, so no worries there.
- General friendliness of teachers, support personnel and students
Again, I’ve never read any thread that didn’t praise the friendliness of and support at their schools as posted above.
I don’t mean to be flip, but none of the questions listed will tease out meaningful differences among boarding schools, especially the four you list as they are generally considered peer schools. My opinion is that these questions are mostly hair-splitting among your choices.
OTOH, there IS a difference in size, setting, and feel among these schools. Deerfield is small compared to Exeter and Choate. The Lawrenceville campus is not as open as Exeter and Choate. So, there are some physical/tradition/feel characteristics that distinguish among them if that makes a difference to you.
And, I agree with @Golfgr8, Deerfield is the outlier on your list, very different culture and look/feel than the others even though similar in respect to your questions. A Choatie would never pick Deerfield, and vice versa.