Hello! ! I've been a "Kafka fan" for about three years now, but have recently realized I've embarrassingly only read one biography ! (Frederick Karl's Representative Man)
Do you have any recommendations for books about Franz's personal life written by academic experts? And is Brod's worth reading?
YES I would recommend reading Brod's biography, but only after reading a biography that's more neutral so you have a fuller picture of what's going on. I haven't read Representative Man in full, but from what I recall Karl leans a little too hard into the "tortured ascetic" trope for my liking. Brod's biography is heavily limited by his circumstances (he can only write in detail about the parts of Kafka's life he was present for, he didn't have access to all the info/documents that modern biographers have) so not a great place to start, but it's still an essential part of the history of Kafka reception and you'll need to read it in order to understand all of the scholarship crafted in response to Brod.
I would recommend reading one of the biographies from the list below and then moving on to the others depending on what you're interested in. In no particular order:
Kafka: A Biography by Nicholas Murray
The Early Years, The Decisive Years, and The Years of Insight by Reiner Stach (this trilogy is the current definitive scholarly biography)
Franz Kafka: The Eternal Son by Peter-AndrƩ Alt
Franz Kafka by Sander L. Gilman
Books that are not biographies, but have a strong biographical focus
Als Kafka mir entgegen kam: Erinnerungen an Franz Kafka edited by Hans-Gerd Koch (extremely valuable firsthand accounts of Kafka from his friends, classmates, colleagues etc. If you can read German and only have time for one non-biography please read this one lol)
Kafka's Other Trial by Elias Canetti (more focused analysis of his relationship with Felice Bauer)
Franz Kafka: The Jewish Patient by Sander L. Gilman (Kafka's views on his body and health in the context of antisemitism, medical advancements, gender and sexuality during his lifetime)
Franz Kafka: Subversive Dreamer by Michael Lƶwy (Kafka and leftist politics)
Kafka's Clothes by Mark M. Anderson (less about clothes and more about aesthetics/popular movements in art and Kafka's response to them)
Kafka and Noise by Kata Gellen (lots of good info on Kafka's interactions with technology and popular media during his lifetime, particularly music and movies)
Kafka: In Light of the Accident by Howard Caygill (deep dives on what Kafka did at work, and how it filtered back into his writing)
Franz Kafka: The Office Writings and Franz Kafka: The Ghosts in the Machine by Stanley Corngold and Benno Wagner (more on Kafka's day job)
Franz Kafka and His Prague Contexts: Studies on Language and Literature by Marek Nekula (focus on Kafka's Czech cultural influences, bilingualism/interest in learning languages)
Franz Kafka on the 10th anniversary of his death by Walter Benjamin
Kafka: A Collection of Critical Essays edited by Ronald Gray
Franz Kafka in Context edited by Caroline Duttlinger
Conversations With Kafka by Gustav Janouch (probably fictionalized account of Janouch's teenage friendship with Kafka, was published as a direct allusion/response to Eckermann's Conversations With Goethe to further mythologize Kafka, please exercise the criteria of embarassment and multiple attestation liberally when trying to read this)
The Nightmare of Reason by Ernst Pawel (kind of melodramatic and silly but like, sometimes that rules)
Kafka: Poet of Shame and Guilt by Saul FriedlƤnder (the rumor is out: does Franz Kafka is gay? Author seems to conflate being gay with literally anything that can be considered "sexually deviant" so watch out)
Franz Kafkas offenbares Geheimnis: eine Psychopathographie by Günter Mecke (you know someone's gonna have awesome takes on Kafka's sexuality when he starts bringing up hieroglyphics)