Do you have a strong preference for one over the other? If you do, go with it.
I wouldn't let your current furniture or wall color dictate the color of your flooring. Flooring is an expensive and permanant choice. It's more likely that you'll repaint your walls or replace your sofa at some point than tear out your wood flooring!
Dark wood flooring lends itself to a slick, sleek, sophisticated, modern, contemporary style. Medium tones work better in a casual, country, or comfortable setting. So, what's the feeling that you're going for?
My personal choice (if I were lucky enough to be in your position!) would be the darker flooring. Darker colors DO show dust, though ... medium colors tend to hide it better. You might have to work a little harder to keep the darker color looking great.
Just go with what you love. Floors are an investment, and you'll be living with your choice for a long, LONG time!