Kaytee Clean & Cozy is my go-to, I order it in bulk bags off of Chewy.com
it's much cheaper than buying it anywhere else, plus I end up buying enough of it that I get free shipping. I used to use Carefresh but I've switched as I really think that Carefresh is dusty (even though the bag says it isn't) and honestly the Kaytee is softer. I use exclusively Kaytee for Pip, and I mix substrate for my gerbils so at least I know it's good if you feel the need to mix a few different kinds!