Everclean ES, hands down. There was a thread on this a few week's ago, so you might want to do a search.

Yup--EverClean ES!

Just remember that cats don't like any scented stuff. I have to keep reminding myself of this, as I love the pine scent. As far as the cats are concerned, the less scent, the better.

And here's a link to at least one of the recent discussions on this subject. Good luck with your research.
http://ths.gardenweb.com/forums/load/pets/msg081147423587.html

I buy anything on sale. Usually Fresh Step or Tidy cats, but one or more of mine like the old fashioned clay kind. Five litter boxes all in the basement and a big one upstairs has scoopable whatever. I got Yesteday News one time and it sat unused till I threw it out. Not one of the five cats used it.

I use the "Oil Dry" clay that is very cheap at Walmart and Sam's Club. I put a couple of generous scoops of baking soda in with it (which I also buy in bulk at Sam's Club) and it really takes care of the odor.

I use the dirty litter in the winter on the driveway away from the house where I won't smell it.

I use BJ's Wholesale Brand of scoopable litter. It works great and you can't beat the price - about 8 bucks for 40 lbs.

I know many people use clumping clay (sodium bentonite) litters with no problem but they do have some disadvantages.

The clay is strip-mined. Strip mining is as the name implies. Heavy equipment strips off the top layer of earth to get to the seam of clay, which is often quite thin. Strip mining is an incredibly destructive process that has wiped out thousands upon thousands of acres of land and removed millions of tons of earth.

The problem with these products is they produce a lot of dust (although some brands claim that the type of clay they use produces a dust-free product), which contains silicon particles that have been established by the International Agency for Research on Cancer as a known human carcinogen. Clay particles tend to cling to your cat's fur and in-between their toes. In addition to leaving dusty cat prints on your floors, breathing these particles can cause respiratory infections.

I tried several brand-name clumping litters when I got my cat and we both coughed and sneezed. Swheat Scoop was recommended to me by a customer at PetSmart and I gave it a try. It doesn't clump as firmly as the clay litters but it does clump and if you scoop gently it is easy to deal with. There is some dust but the dust is heavy enough that it doesn't fly up in the air. I have no odor in the room from the box if I scoop every day. And the best thing is the cat and I don't cough and sneeze any more.

Okay, the best seems to be the Pro Pet Fresh Results. The Back to Nature ended up not helping the ammonia smell, but the Pro Pet does and has more of a "woody" feel to it than clay. So far the best one!

I haven't used clumping litter much. With a CRF cat the entire box would have been a clump in one day. However he is no longer with us and DH bought clumping by mistake so we are using it. It's working well. He bought Fresh Step but I tried Ever Clean based on the recommendations. Right now I have three boxes with three types of litter - regular Fresh Step, Fresh Step Scoopable and Ever Clean. The cats like the clumping better - to the point the regular litter box isn't being used much. They don't seem to have a preference of one scoopable over the other though. Ever Clean was a bit more expensive than Fresh Step.

This is a great example of why cats who are indoor/outdoor are so great. They ONLY use the litter box if there is no alternative. When it is below zero out and several feet of snow, they are kept indoors. They are great about using the litter box (kitty pool) but sure do prefer outdoors even if it means relieving themselves in the snow.

Ain't nature grand???

Best by far, and I've tried them all, is NonScents Odor Control additive - available on Amazon. You can even get a free sample I think. No odor and best of all no scents and no dust! Amazing. I think it has some antimicrobial feature that kills off the germs. I don't know but it really works.

Precious Cat by Dr. Elsey.

A lot of them say dust free but wow there is a lot of dust. Would love an explanation of this, lol.

A second (and third from my cat) for Precious Cat. Used wheat litter for years but it was inconsistent and got too dusty. Precious Cat is completely odor free and dust free, but is still a small granular form, like old-fashioned cat litter. Good for kitties who like to dig in it, like mine does.
I had trouble finding it locally, even at the big pet stores. It has become very popular lately. I ordered it from Amazon last time and that worked great. Free shipping and fast delivery. It is a very dense material, though, and may seem heavy compared to other litters.

Look for the dark blue bag.

I bought some Ever Clean today and used it for one box out of the two.

The other box is still the no-name bulk unscented clumping clay litter from the pet store that I normally use.

We'll see in the next few days which is preferred.

We actually switched to the Dr. Elsey Ultra Precious Cat recently. Figured we'd give it a try, as we were becoming more and more fed-up with the overly-perfumey fragrance of the Unscented/Fragrance-Free EverClean ES.

The Ultra Precious cat has a lot of pluses; it is, if not entirely dust-free, pretty close to it, has no scent, perfume, etc., whatsoever (hooray!), and is much more economical (than EverClean--40# bag for less $). It seems to neutralize cat urine odor just about as well as EverClean. It might not be neutralizing poop odor quite as well, but one of our two cats in currently on Metronidazole, so it's possible the litter might work as well under "normal" circumstances. At this point, now that the tummy issue is clearing up, litter box odor is within an acceptable level (and my tolerance for any odor is not high at all!).

Litter does track/scatter just as much as the other(s).