The issue of EC’s was best addressed at one of the early info sessions we attended several years back at MIT - some parent asked what EC’s are viewed more favorably by the admissions department. The admin officer paused for a moment, then told the group something like -
“If I tell you it’s turnip farming, because we admitted a turnip farmer last year, then I would expect we’d see at least a couple dozen turnip farmers apply next year. No offense to any turnip farmers in the room right now. The whole point of extra curricular activities is that they are something that you care about, that you choose to do when you are not simply being a student. We have many applicants whose EC seems to be studying for ACT and SAT tests - they may be driven to better themselves, and if they can express this well, we aren’t going to fault them for it. Anybody can choose to do whatever they like with their free time. I really mean it. We are only going to accept a small fraction of applicants, and at the end of the day, there are really no big differences between the accepted and rejected piles. Don’t try to make yourself look like the ideal applicant because it does not exist. Take the most challenging courses that your school offers, do very well in all of them, get top scores and grades, and when it comes to extracurricular activities, above all just be yourself. If your EC is a part time job, or caring for younger siblings or grandparents while parents work, that’s a part of what you do aside from studying/classwork. Let that shine through in your application. And did I mention I don’t even like turnips?”
I am paraphrasing as it was a while ago, but I am certain I got the gist right. We came away with a very favorable impression of the school, and the admissions department in general, as the presenter had what I feel was the perfect answer (and his delivery was terrific - he had the entire auditorium riveted to his every word).