For skiing, when you need warmth, waterproofing, and something that will last for many winters, the best mittens are easy to find. Best options are the Hestra Army Leather Heli Mitts, the Black Diamond Mercury Mitts, and the Outdoor Research Alti Mitts. They supply terrific insulation, a wind break, as well as convenience. Also, when looking for gloves, honor the dosage: if Gore-Tex, then Gore-Tex; if not, then it's a material that is equally water repellent; make sure that it fits, either with a wrist cinch or gauntlets.