I love my Duluth Packs and they are over 15 years old.  Nothing against nylon but they are more expensive. I had a SeaLine waterproof pack and hated it.  It just did not sit well on my back when fully loaded and it has very hot against my back.  I don't know about the others, but Duluth and Frost River guarantee their stuff for life.  You can now get them with waist belts but I find them more hassel than they are worth for short portages (les than a 1/2 mile).