My kids love so many of the ones listed above, particularly the Ramona Quimby and Chronicles of Narnia Series.
FYI, Audible is currently running a kids summer sale and a lot of these titles are included. All of the books in the Redwall series are on sale for $3.95, as well as Charlotte's Web and The Lion, the Witch, and the Wardrobe. Tons more, too!
The Tumtum and Nutmeg series by Emily Bearn is pretty fun. And while it's neither fantasy nor animal-centric, I also have to recommend Anne of Green Gables narrated by Barbara Caruso, if for no other reason than it was my all-time favorite audiobook when I was your girls' ages. :-)