Synthetic-fill bags cost less than down, and fare better should the insulation get wet. You might choose one for either reason or both. Just make sure it's a bag like the Cochise, which is as warm as advertised, thanks to an adequate amount of Climashield XP fill. (Our testers routinely find that many synthetic bags are not as warm as their temp rating suggests.) We also like this bag's Flex construction, which incorporates stretch baffles and stitching across the torso area for increased elbowroom without extra dead space.
The full-length side zip runs diagonally from ground level to hit the hood near the collarbone, making it easier to reach for midnight exits. The 50-denier polyester shell will take a ton of abuse for years to come, but the penalty for the bag's warmth and durability is extra weight and bulk. Women's model is the Yachiyo. $159; 3 lbs. 4 oz.; 15°F