I must have tried every cat litter out there when my Merlin became an elderly house-bound cat. Personally, I prefer the clumping. The stuff that turns to sawdust created so much dust and affected us in terms of allergies. The crystal type smelt absolutely horrible, and we often found a puddle of wee at the bottom of the tray. Our favourite is Extreme Classic There is hardly any smell, and very easy to pick out the used bits. Yes, you will go through a fair amount, but it clumps so well that you can pick out the used blocks and then top it up. With non clumping you tend to have to change the whole lot more often. Word of warning tho - with a covered tray you might find the clumping stuff doesn't work as well - when we used a covered tray for our new kitten, the used bits were more like clay than solid rocks. We think it must be something to do with air flow.
As for the auto-cleaning trays. I seriously considered one, but read too many bad reviews - cleaning rakes getting stuck etc. I honestly think they'd be more hassle than they are worth, and that is saying something coming from miss gadget over here.

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