If your site has a lot of written text on it, use backgrounds that contrast well with your font color. Almost everyone these days work off their computer. People want to minimize eye strain. Make it easy for them to read what you have to say.
Studies show that a light background contrasts well with dark text. This is because we were trained since childhood to read this way. This is why books, newspapers and magazines are printed using this contrast. They want to make sure it is easy for us to read their material.