First of all, congrats! :) Those are all incredible schools, and you (honestly) won't regret going to any of them.

I recently graduated from MIT (undergrad, CS), have lots of friends who went to Harvard, and have family who went to Stanford (and I work in SF).

It's important to realize that college won't define your career. It's the first step where you'll learn fundamentals and deep-dive into real math, science, and literature. Just as important are the ways you spend your summers, the books you read, and the friends you make.

Also, there's no "perfect" fit of a school. I was passionate about music, and always wished MIT had a stronger arts department. But you should be open to the unexpected. I joined the rowing team on a whim, and became a Division I athlete-- something I would have never expected or planned.

With that said, here's what I've gathered:

MIT is hands-down the best engineering school in the entire world. In 2 years you learn more than most people do after a masters. Downside is that it's not very well-rounded, but that's kind of the point. As a friend's father once said, "You don't go to a candy shop to buy broccoli." People routinely make jokes about calculus and wear shirts that say "Nerd Pride." Places like the Media Lab are an amazing fusion of art/science/design/engineering, and MIT is a respected hub for world leaders. (I met the Dali Lama and Bill Gates in the same year.) MIT was the birthplace of most of the tech we use today. People like Richard Feynman went to MIT. At MIT I learned how to pick locks, spin fire, write LISP, and laser-cut my Christmas gifts.

Harvard will teach you to think about how the world works and how to organize people. Many people don't realize that Zuck was actually studying psychology at Harvard, and Facebook was predicated on how people think and interact. There's lots of "old money" at Harvard, and it's not the same kind of meritocracy as MIT. Some kids are olympians and others the sons/daughters of politicians. Al Gore and Tommy Lee Jones lived across the hall from each other at Harvard. Harvard grads often go into finance, international relations, law, doctoral science studies, etc. Harvard has lots of grade inflation.

Stanford is a mix of the two, with incredible science+engineering, but also sports and liberal arts. You'll find the cliche fratboy bro, but then learned he aced his SATs. Palo Alto is beautiful and sunny, and the vibe is locked with the startup world. Professors regularly consult/advise companies, or leave to start their own. Apple/Google are involved on campus, and there's a true spirit of innovation amongst the students. (nb. distinct from invention.) In particular, graduates of the Symbolic Systems program often become Associate Product Managers at Google and/or found their own companies. (Snapchat/Instagram/etc.) They aren't as nerdy as MIT, but they're still wicked smart.

There's no "path" toward entrepreneurship, but there are many successful founders that started with a hardcore engineering background. (Elon Musk was actually planning to pursue a PhD in physics at Stanford before dropping out to start Zip2.) Rigorously learning first principles in mathematics, chemistry, physics, and programming is key to later taking-on large projects, like building rockets.

I would just say matriculate wherever has the people you want to spend 4 years around. It's your peers which push you and teach you the most, and later will become your cofounders or employees if you do a startup. Even if the school isn't perfect, you'll find your people and your own way.

(As an aside, I actually gave at talk at MIT last fall about how I got into startups and rounded-out my education. Just more datapoints for how I navigated. https://www.youtube.com/watch?v=tJcCwUOsY_k )

Just make sure to major in science/engineering and work your ass off. :) Feel free to ping me if you have specific questions. I'm mg@mit.edu.