WM Summerlite. If you fit in it, of course. This thing packs so small it's amazing. My second choice (for colder climates) is the WM Versalite Super. It's funny I went mountaineering last summer and I was the only guy that ventures into the lightweight gear. On the way up to base camp everyone else had these huge packs and tents and sleeping bags hanging off their packs. I had my WM Versalite super and my BD Lighthouse tent stuffed in the bottom of my Vapor Trail pack and everyone kept asking me if I was sure I remembered to bring everything I needed. Someone specifically asked "Are you sure you didn't forget your sleeping bag? Where is it?"