I've spent a lot of money trying to solve this problem.. including buying the $700 litter robot, etc.. (that thing is not worth it at all btw)

The best litter box is the Tidy Cats Breeze (if your cat accepts it)

Bad smells (usually) (mostly) come from urine mixing with feces.. this litter box separates urine from feces, and the pellets and pads are engineered to control odors. Plus, the pellets are easier to cleanup than other boxes..

If you use that litter box, and feed your cat foods that it digests well - which in general usually means feeding your cat healthy food.. then cleanup is going to be very easy and painless.