To make the proper buying decision, you need to speak the language. Along with a myriad of construction details described in the individual reviews, three major factors distinguish the jackets we tested:
Fill power: These coats contain 600-, 650-, and 700-fill-power goose down. Ounce for ounce, you get more insulating fluff from higher fill-power ratings (850 is the fluffiest down currently available, though rumors suggest that higher ratings are on the way). We didn't notice differences in warmth based on fill power alone, but we did note significant differences in compressibility. As a rule, you pay more for the higher rating.
Hoods: Insulated hoods make a jacket warmer. They also add bulk and cost. Some testers think a hood is worth 10 times its weight in hot cocoa. Others think hoods are superfluous considering that winter campers are already wearing hats, balaclavas, and hooded rainjackets.
Weatherproof shells: Some jackets repel wet snow without a covering rainjacket. Others get soaked at the brush of a flake. In dry, cold conditions, waterproofing makes little difference, but in wet snow or transitional situations, the weatherized shell saves you the hassle of having to yank out your rainjacket quite so often. Unfortunately, it also adds to the cost.