Joyce or Kafka?

In one of my classes, we have been batting around in my class the assertion made by a writer friend of mine that "Joyce used to be the most influential author of the 20th century; now it is Kafka," This excited some very interesting positions pro and con. The idea of Kafka's influence is, I assume, in magic realism, the interplay between high fiction and genre fiction such as horror, fantasy, and sci fi, and a more felt political imperative, and this had influences beyond Joyce's 'merely' formal and experimental ones.......this has its temptations, but I wonder if what my friend was really saying was, Kafka's German-Jewish-Czech political context was more interesting than Joyce's Anglo-Irish-Catholic one, and I am not sure if this is true, certainly the influence of Joyce on postcolonial fiction belies this..and I also wonder if the more important idea is just that K and J are comparable....