That's indeed a very personal opinion..
I found Kafka at least entertaining and that's more than can be said about most other stuff you've got to read in school.. -personally, I hated "Effi Briest"(Fontane) and "Die Wahlverwandtschaften"(Goethe).. But I liked "Der Richter und sein Henker" (Dürrenmatt)..
After school, I read some more suiting "Klassiker": Kassandra by Christa Wolf, lots of Kafka, Camus (but he's not German), Lenz, Hesse and Frisch.
Studentin, do you like poems? Then you might like Rilke (there are good translations into English, too)?
And there are a few good German writers of historical novels: Rebecca Gable (I have to recommend her, using one of her main characters as a nick ;), Wolf Serno, Ulrike Schweikert, Tanja Kinkel, Petra Oelker (whodunnits, set in or around Hamburg)..
The cat has mentioned Petra Hammarsfahr, I like her a lot, too, though her books are quite disturbing from time to time, describing incest, pedophilia or sexual abuse..
/personal opinion/ Die Buddenbrooks ist ein scheußlich langer und langatmiger Roman.. Hast Du den tatsächlich ganz gelesen, Eifelblume? Hut ab! /personal opinion/