This topic from Long and Short Reviews took a bit of consideration, as a lot of the books I read were chosen because I saw and liked the film. As for TV series, I don't really watch them. However, I read two books recently which I think would be interesting to show on film.
As a movie, I would say Klara and the Sun by Kazuo Ishiguro. Set in a dystopian future where near-human robots are kept as companions, this is the story of Klara and the secret of the family she goes to live with. It's a slow burn, but would make for an interesting and thought-provoking film.
As a TV series, I recently read All Girls by Emily Layden, which is a series of interconnected vignettes set at a girls' boarding school, all leading up to a shocking climax. The episodic format of the story, each chapter following a different character, would work well in a TV series. As it's a fairly new release, there's still time for someone to pick it up.
So what would you like to see as a movie or TV series?