If you don't want a wicker basket, then Topeak make metal baskets that attach to their bike racks. They also sell connecting brackets/quick-connect mechanisms for their bike racks that you may be able to attach to a basket of your choice - this will allow the basket to be quickly connected to or removed from the pannier rack.
I've been using a Topeak rear rack for a few months now on a commute bike and find it good (i.e. robust, which is about the best you can hope for from a pannier rack). Their quick-connect mechanism is okay too, quite simplistic and under-engineered which is arguably a strong selling point. Their range, including baskets, separate quick-connect mechanism, etc., is visible here
. I'm not sure that ChainReactionCycles has the best prices for Topeak stuff, I just chose their link as they sell quite a wide range of Topeak kit.