Hi, we've always just used a normal open litter tray. Think the type of litter you use goes to solve the stink problems. We've tried the cheapest ones to the more exp ones. Find the supermarkets own brand that clumps are the best for ours. Never really found it to smell too much, just clear it out with the scoop and nappy bag

Suppose the covered ones would be good if you had a cat who insisted on flicking cat litter all over the floor though.