Fear and Loathing is decent, but probably needed to stick closer to the source. The idea of Ralph Bakshi doing an animated version of Ralph Steadman’s illustrations (maybe with Dr. Hunter S. Thompson narrating) sounds very appealing to me.
The Harry Potter series probably would have worked better in today’s age of “prestige TV adaptations,” as that format would allow for fewer book deviations (e.g., making Ron an idiot, deleting subplots, and trying to soften Snape).