Given polar weather, finding a good comforter is all about Goldilocks temperature and moisture regulation. Too warm is no better than too cool; not enough moisture wicking and you're sweating through your mattress. Our full guide is still in progress, but after a few dozen hours of research and preliminary testing, our pick is LL Bean's Baffle-Box Stitch Down Comforter, which starts at $209 for a twin bed and runs up to $359 for a king.
We found 600 fill power was the right amount of down; 900 fill costs more and looks lush, but without measurable improvement in comfort and warmth.
We tested comforters in New York City in the middle of winter with the window open and the radiator off. Both sleepers woke up toasty, but not sweaty. Our tester in San Francisco also rated it highest of the comforters sampled so far.
If you've got allergies, we recommend the Australian Wool-filled Sateen Cotton Comforter ($110). Wool trumps down alternatives because we found that synthetics tend to run much hotter, leaving sleepers sweaty and uncomfortable by the end of the night.
For more on our preliminary report, or to ask our writer a specific question, check out our guide.