I worked in a large successful tech company right after school. One of the best periods of my life. I learned a lot, worked on really cool technology, and I was treated well. I left for reasons unconnected to them, with much regret.

There exist great start-ups, great big companies, lousy start-ups and lousy big companies. And within great companies, big or small, there exist lousy situations. Your immediate boss and your colleagues have more to do with your happiness than almost anything else.