White is the serious professional's colour of choice. While other shades are yelling for attention, white gets noticed just by being there. In major or minor roles on a football boot, there's none more striking in contrast than 'the colour that isn't'.
For a clean-cut, fast look that stands out, but still maintains it's integrity and style you can't beat white. Whilst less popular with social players as you have to clean your boots all the time, white is popular with the pros and perhaps you should be cleaning your boots more often anyway?