Regular Kyurem is still a better choice, as its slightly higher Special Attack means stronger STAB Blizzards. Kyurem-B's physical movepool is very shallow, as it doesn't have too many physical moves to take advantage of its 170 Attack.
Use Landorus' Therian Forme (since its regular forme seems better suited for Sanstorm teams) for an offensive pivot or Gastrodon if you want to check Rain teams. Up to you, really.