I particularly like this Salewa sleeping bag. The inner material is one of the most comfy, and there’s a good stretch too it meaning wrigglers like me can get comfortable. The 3D flex, I think, are little flares in the fabric that allow movement. The fill power isn’t the highest here, so it is bulkier than some, but it’s still a great price for a warm sleeping bag (although not the warmest here with a comfort rating of   -9°C. There’s another zip around the feet so it can be used as a blanket, for some reason.