I have destroyed a few bagpacks lately (the shoulder straps have been ripped off or the zippers have died) and I am now out to find a bag pack. I have mostly used Oakley and Lowe Apline untill now, but I wonder if I can find better quality elsewhere. I am looking for something in thr 40-15 litre range and it has to be burly and be able to hold up for some tough trekking. Advice need.