Modern, preferably non-standard idiom, or at least with a very strong intellectual overtone. I like books where nothing much happens but I am given plenty to think about. Just as I don't like structure in music ,plot is unimportant to me in literature. I cannot handle big, complicated sagas with hundreds of characters or "blockbusters" with a lot of drama, romance, sex and fighting. These leave me cold after the first few chapters - if I ever get that far.
I like Joyce (obviously Finnegan's Wake) , Huxley, Virginia Woolf, some of Burgess, some of John Wyndham, all of Janet Frame, much of Eliot (poetry), J.B. Priestley, Guy de Maupassant, the ghost stories of M.R. James. Many more, but all in some sense lying within the above criteria.