What are some of the best ultralight sleeping bags? There are so many to choose from! How do you decide between down or synthetic? What style of sleeping bag is the right fit for you? Do you prefer a sleeping bag or a quilt? And what’s all the rage about quilts anyway? The market is full of good quality, ultralight sleep systems. When discussing sleep systems, it’s extremely difficult to report as to whether the bag/quilt lived up to its temperature rating because everyone sleeps differently.