I will start nominations with
The Wonderful Wizard of Oz by L. Frank Baum.
We all know and love the movie, but as we all know "the book is always better than the movie". Let's find out if that is true and discuss together...
It is available as an omnibus put together by
Nate the great in the Patricia Clarke Memorial Library in several formats:
ePub,
Mobi (Kindle) (and others). A stand-alone version is also available with illustrations
LRF and
Mobi (the LRF format has more per the comments.)