I have the Eberlestock Just One and have found that to be the most comfortable pack out of the Badlands 2200, Badlands Sacrifice, Badlands 4500, and Mystery Ranch NICE Frame. I have not had any first hand experience with Kifaru, but I hear they make the most comfortable heavy hauler on the market. The Badlands Sacrifice was extremely comfortable under lighter loads. I love how the Just One fits and packs so well. I even sold my NICE Frame & 4500 so I could get a Dragonfly in the Military style, the military style is for both work and having a solid front panel instead of a mesh.
The Eberlestock J-Series packs seem to max out at about 18.5"-19" torso length in my opinion, but their waist-belts are amazing for people with smaller waists. I have about a 28" waist and the Eberlestock waist-belt is by far the best I have used. I would actually wrap that around under the Mystery Ranch and Badlands waist-belts to improve the fit. I also love the versatility of the J-Series type packs over traditional packs that stand a good height above your head. I like having the increased mobility of being able to crawl or climb up tough spots more comfortably. Yes its true, the lower riding design hurts it load hauling capabilities. Another advantage of the J-Series packs are that the aluminum stays double as splints, but that is not a huge deal since sticks are quite abundant in the backcountry.
In the End, choose the pack that best fits your body and your needs. When it comes down to weight-to-performance ratio, look no further than the Kifaru UL 3700 or 5200 packs. If at all possible, try out every style of pack you can before settling on one, even though it is very hard to get your hands on a Kifaru or Mystery Ranch. It would be great if there was a program setup that allowed people to rent packs, particularly Kifaru & Mystery Ranch, for a couple weeks so people could test out which one best fits their needs.
Good Luck & I hope you find the pack you were looking for.
