I like the Wald folding baskets. Sure they weigh a bit more and are always on your bike, but you can just throw regular grocery bags in there for grocery shopping and for day to day commuting, you just throw a normal backpack or whatever you want in there, take two seconds to put a bungee cargo net on top and you're good to go. Can hold a ton of stuff, super easy, super durable, and adaptable to carrying just about anything. Oh and they fold up flat to the rack when not in use, so not as bulky and don't raise your center of gravity like tying a milk crate to the rack. Not what you asked, but it works.