Everyone has their favorites. We've had the best luck with Scoop Away scoopable litter. To me it's the cleanest scooping litter I've come across. I've tried many kinds and brands, but none worked as well for us as Scoop Away.
EverClean. One of my cats won't accept just any litter but this brand she accepts (this brand only, nothing else is good enough) and I have to say that it is very good. It makes really firm and easy removable clumps.
I use the scoopable arm and hammer litter. You definitely want litter that's scoopable because it's cleaner. As soon as my old litter is gone I was thinking of using the flushable stuff. This way it's goes in the toilet instead of the trash. This way smells can be quickly eliminated.