Steppenwolf is about a man torn between society and his need to reject it. Zoë Winter calls it one of her favorite novels in her video on The Age of Reason, and says the two have a similar mocking yet comforting tone. The difference, she says, is that Steppenwolf ends on a note of hope.
I have two other Hesse books on my list, The Glass Bead Game and Siddhartha, but I want to start here.