The ripstop nylon is the best. It washes well, dries quickly, and is really strong. The seams hold well too. The fabric is a bit expensive, though. I found a set of bags, already made, five bags for $17, and that includes a pouch. That's actually tough to beat, even making them yourself. A lot cheaper than envirosax, chico bags, baggu and those fancy-shmancy ones. The bags I found were at
--Dale--