Radial lacing is preferable for low spoke count front wheels because it makes up for some of the stiffness that is lost from removing spokes. Its also very easy to build a radial laced wheel. The only problem with radial is the additional stress on the hub flange. But with fewer spokes, its less of a problem. As a general rule, if the hub isn't specifically rated for radial, then use 1x...its almost as stiff as radial but easier on the hub.

Never radial lace a rear wheel, of course.