Different waxes are made for different temperatures and snow conditions–choose one appropriate for the local scene. Talk to someone at a snowboard shop in the area to find out which variety is the call. If you're unsure of the conditions, use a good universal wax with the broadest temperature/humidity range.
When in doubt, err on the side of colder (harder) wax with some graphite content. Harder waxes last longer (especially along the edges where pressure is most concentrated) and tend to be more forgiving in varied conditions. Additionally, graphite neutralizes static created by friction between the base plastic and snow as the board slides. This static electricity attracts dirt and moisture that cause drag.