I currently use the Wald 14.5 x 9.5 x 9 basket; it's zip-tied to my rear rack and is pretty much the perfect size for my backpack to sit upright in. I also have a set of the folding baskets; I've liked them since I was in college and found one by the side of the road once...I used it for years. They work very well, but they are also quite heavy (and I'm far from a gram, or even pound, weenie). If you found you used them regularly, it would be worthwhile having them, but if you just put them on because you might occasionally have some use for them, I think you would get tired of the extra weight...they weigh 2.75lbs each.