Probably The Wonderful Wizard of Oz just for old times sake. Although I read all of the Baum books, we only actually owned the first. So that was the one I read and re-read and re-read in childhood. However, I admit I always loved Ozma of Oz because of the lunch-pail and dinner-box trees. I’d still really like a dinner-box tree in my back yard. I’ve never read any of the children’s Oz books other than the Baums – at least not that I remember. I owned the whole set of Baums at one time, in the Del Rey mass-market paperback editions. One non-Baum Oz book I do love is Barnstormer in Oz – I sure wish Farmer would write a sequel.
Jess