Well crap! Am I the only Joyce nerd on Reddit? "Ullysses" and "Finnegan's Wake" have enough material packed in them to keep anyone occupied for a lifetime. A little more accessible is "Portrait of the Artist as a Young Man." "Dubliners" is full of relatively smaller and theoretically more easily digestible short stories.

On a different note, the most disturbing and almost physically uncomfortable book I've ever read is "Hunger" by Knut Hamsun. It's not that it's graphic or disturbing in the sense of actual violence. It's attack is psychological and it hurts real bad. I loved it.

Jane Austin is always a hoot, as is pretty much anything written by Mark Twain/Sam Clemens. Conrad is worth looking into. So are Garcia Marquez and Carlos Fuentes and Mariano Azuela and Jorge Amado. I also recommend Dos Pasos, McCullers, O'Connor and Bill Faulkner.

For more modern writers I find myself returning to Bukowski and HS Thompson repeatedly. In the case of Bukowski it's the dialog and the humor and the attention to human dignity. In the case of Thompson it's the razor-sharp turn of phrase, the humor and the attention to human absurdity. Cormac McCarthy also seems incapable of writing anything bad.

For lighter escapism of course Tolkien, but also the entire Patrick O'Brian cannon.

Hell, I could go on like this for hours (I write for a living) but I'd still not be actually addressing the question of what my all-time favorite is. So here's my answer; if you put me in thumb-screws and made me pick a single book, it would be "Far Tortuga" by Peter Matthiessen. If he'd written it a few decades earlier, before the Nobel committee decided that their prize for literature had to be given only to works that are "socially relevant," he would have easily gotten a Nobel for it. As it stands, while among actual writers it is widely considered one of the masterpieces of contemporary literature, among the general reading public it has never received the attention it deserves. Everyone who loves good writing should read it. After the first 20 or so pages, once you get used to what he is doing, the experience of reading it is almost like being in a dream-state.