Catch-22? That book drove me absolutely insane. I think I could appreciate the point but after awhile it was like the same joke(?) about the absurdity of the world being told 222 times in a row.

What makes you list it as one of your top two?

Sometimes a work is best appreciated as a meditation on a particular feeling, and the evolution thereof. Catch-22 was like that for me.

It is the same humor, told over and over, but at the beginning of the book you're laughing while at the end of the book you're crying because the humor in the situation has turned to horror at the inhumanity of it.