First off here are the kitties: ~4yr old male DSH, 2,~8 month old DSH kittens
Box: large regular covered box, and large Omega Paw roll-away box
Litters I've tried:
petsmart Exquisicat clumping clay unscented
petco brand clumping clay litter
Scoopaway (scented) clumping clay litter (for brother's cats)
Arm & Hammer extra strength (scented) clumping clay litter (for brother's cats)
world's best cat litter regular and extra strength
"fresh idea" (or similar name) corn-based pine scented litter from wal-mart
Feline Pine Scoop (clumping from pine)
Papurr scoop (clumping from paper)
Chicken layer granules (corn and other grain chicken feed used as litter)
Of these here are the advantages and disadvantages I've noticed...
Clay Clumping litters:
Very good clumping usually (the scoop away was top on that mark)
Very good at odor control (varies by brand)
Relatively cheap (depends on brand)
Readily available in most locations
Very heavy, so not easy to haul, scoop, and less area coverage per weight (same weight box as the pine or corn litter covers less area in the litter pan)
Can be very dusty- silica dust is very harmful for humans and animals to breath in
Scented litters can be offensive to you and the cats
Harmful if swallowed (esp. for kittens..turns to basically cement in their intestines)
Natural litters-(note this is "across the board, my overall favorite is WBCL)
Flushable!- although some suggest not doing so, especially if you have a septic tank
Light weight- same weight as clay covers more area, easier to lift and scoop
Not dusty- MOST types are not nearly as dusty as clay, in any case it isn't silica dust so not as harmful if it is inhaled (WBCL has virtually no dust at all while feline pine scoop is VERY dusty IMO)
Good for the environment- renewable resources
Not harmful if swallowed
Generally not as good clumping as the clay
Generally more expensive (per weight) than clay (except the chicken feed)
Can be harder to come by, not sold everywhere
Some types can be lousy on odor control
So, overall, If I had to pick one of each, (best all-around)
I'd say look at scoop away (as unscented as possible) and WBCL...
Also note, that you can email the companies and they might give you coupons to try their product (this worked for me and WBCL)
You can also get non-clumping natural litters like yesterday's news, feline pine, swheat scoop, and even wood-stove pellets. With those, you scoop the poo and leave the urine to break down the litter in the bottom of the tray. I have not tried any of those before, so can't give feedback on them.
I am currently using a mix of WBCL and papurr scoop. When I am out of the papurr scoop I will be trying a mix of WBCL and feline pine scoop.
When I flushed mine down the toilet (I just throw it out now) it is important to note that you can only dump the clumps and poo down the toilet, not a whole box full... I usually let mine sit for a while to degrade, then flushed it down. Didn't have any problems with any of the ones I listed.