I have used the Deluxe Performance bag and it is excellent. It's large, but not cumbersome. It's stiff and has multiple exterior pockets that are very handy. It's water proof or repellant but I spray my bags and panniers with waterproofing stuff anyway. The thing I like best is that it has four attachment points instead of two large ones. With fenders, the two large straps are difficult to attach (for me) but the four corner attachments work very well. I've used it on five day tours over gravel and in pouring rain and it's held up perfectly. It's only about $35.00 on sale (which it always seems to be. The other bags mentioned above are all fine but Topeak works best with only Topeak racks and Arkel is excellent but expensive. The biggest problem is that you have to get over the Performance name and recognize that some of their stuff, although not a brand name, is excellent. Good luck.