I have read a few hundred books, so this is a tough call for me. First, I must say what makes a book great for me:
I. It must have a great plot - the characters have to be interesting and they should develop as the story goes on. If, at the end of a book, a character remains the same as in the start, that is likely to have been a bad novel.
II. The writing must be satisfactory - I'm not talking about grammar and spelling, which are basic. The prose must have quality and the style must be unique (I can't point out something worse than the feeling that what I'm reading is derivative of someone else's work). Authors who delve into their dictionaries so as to find and utilize archaic terms to showcase unordinary literacy are also fairly dismaying.
III. The story must bring me something new - it ought to introduce me to something that I have not seen before and which excites me: a new culture, a different country, diverse characters, life-changing lessons, a particular writing style, etc. When I read a book that feels like everything else 's work, I feel so disenchanted.
With those points in mind, I could point out any of the following books as being among the best I've read to this day: José Saramago's As intermitências da Morte
(Death With Interruptions), George Orwell's Animal Farm
, Gabriel García Marquez's Cem Anos de Solidão
(One Hundred Years of Solitude), Èmile Zola's Germinal
and Franz Kafka's Metamorphosis