I asked this question in the Wisdom of the Crowd:

What color do you prefer for an wristband (for emergency call)

Here are the responses: (44 Votes)

30 % - Blue
16 % - Red
16 % - Yellow
14 % - Black
11 % - White
9 % - Green
5 % - Purple

See the pie chart at:
http://www.tklcloud.com/Crowd2/chart.aspx?ID=2628

CLick here to vote on the current issues:
https://tklcloud.com/Crowd2/active_issue.aspx