I have worked for too many people and companies. What I enjoy doing (and what is more successful for all parties involved) is working with people and companies.
When things or people work together they get things done quicker and more efficiently.
In the past when my work had the most positive effect on the company it was when I was working with them. I can remember moments precisely when I went from working with to for.
Something changed and I no longer felt like my work was adding value to the company or person. When I work with people we can make things better, and more creative, and the results can be more rewarding for everyone involved and the customers will benefit from the results as well.