Not sure if anyone is trill reading this but….. There are lots a great brands out there, obviously some better than others. A couple of things to look for that really make a difference with a hiking pack, especially in a tough environment such as Kokoda, are the harness and the materials.

With the harness system, look for something that has a good solid waist belt, not a soft flimsy thing. The waist belt is there to support the weight (Not your shoulder straps) and transfer it through your hips to your thighs and buttocks. If it is too flimsy they just sag and make your shoulders do the weight baring. This will become very uncomfortable very quickly! You also have to make sure the shoulder straps are snug and comfortable too as they will support some of the weight just not much if you're set up right.

The other thing to look at is the materials used. With the harness system look for EVA foam, most companies now use this but look for something that feels comfortable when pulled tight. The main pack should be as light as possible but rugged. Materials such as Cordura and Rip Stop nylon are pretty tough and generally light. Canvas is very tough but a little heavier.

I could recommend the Xtreme Earth packs. There is even do a kokoda package with a sleeping bag that is great value. The harness is one of the most comfortable I've ever used and it's so easy to adjust to suit. http://www.xtremeearth.com.au