From McMurray, the free chick is usually a male.I'm about to place my order to Mcmurray, the free chick box was automatically checked......I'm on the Fence!
They seem to mostly send out new, rare, or unusual breeds for the mystery chick.
I would say to get the mystery chick, but have a backup plan of making him into fried chicken if he doesn't work out well in your flock.