I have had a backpack for years that I have loved because it had different sections that you could zip on and off. If I just needed a small pack I could just take the basic model but if I needed a lot of things, then I could just keep adding on different pouches. Over the years it has seen its fair share of adventures and it is finally starting to break down. I would like to replace it with something similar but I want to know what is the best backpack material around that comes in the kind of pack that will fit this request?