The Western Mountaineering Megalite wins for serious backpackers due to its 1 lb 8 oz weight and 850+ fill power versus the Kelty's heavier build and 550 fill. The Kelty Cosmic 20 provides solid value at $190 with a warmer 20°F rating and recycled materials. Megalite's 12-denier ripstop nylon shell adds breathability advantages over the Kelty's recycled construction per the provided specs.