I have had small pets all my life. I am allergic to cedar chips and pine bedding, which we now hear is bad for the pets to breath in. Carefresh is not only odor/fragrance free, but it is very absorbent and safe for your little pets.

I litter trained my guinea pig and this is what I use in her litter box.

Pros: compact bag, easy to clean up, different colors

Cons: a little more expensive, but worth it

I only use this for my buns litter box. It works well for that.

Pros: I like the softness and odor control that carefresh provides.

Cons: It's very pricey.

In addition to the "cons," it just doesn't seem to do as well as Cell-sorb as fighting odor. I have yet to try woodypet, but this just doesn't keep the stinkies away.
Plus it sticks to any wetness on the rabbits.

Pros: It's very comfortable

Cons: Doesn't mask odor, gets all over the place

I've used Ultra and regular Carefresh, and the only difference I've SEEN (all caps intentional!) is that the bunny pee is very obvious on the Ultra's bright white litter. Maybe not a biggie if your little one is in a hutch or someplace inconspicuous, but my bun's litter box is in plain view! Regular works for me :-)

Pros: soft

Cons: wrong color!

We switched from Woodypet pellets to Carefresh bedding and our ferret loves the stuff. It is very soft and cozy for him and it doesn't stick to his fur. Also, it seems to be quite absorbent.

Pros: Very soft,does not cling to ferret fur

Cons: expense