Ubik
Mind blown!Philip K. Dick is generally very welled loved by the sf readership, nobody writes quite like him. His novels tend to mess with my head and leave me WTF-ing, wondering where I am and what is going on. In a good way of course.
It is difficult for me to choose a Dick favorite, I have never read anything by him that I did not like. Still, if I must choose one I would choose Ubik. The different layers of reality remind me of The Matrix, Inception and Ursula Le Guin's The Lathe of Heaven. None of them are very similar to this book though, nothing is.
Dick tend to be criticized for poor writing style and characterization, I have no such issues with his work. The prose of Ubik is straight forward which is great for conveying the weirdness of the story, if Dick wrote this book in complex poetic prose it would probably render this book incomprehensible to me. As for the characters, they seem like pretty odd individuals to me, they tend to do and say the most unexpected things, I like that about them.
If you have never read any PKD book before you need to rectify the situation ASAP, Ubik is a great one to start with.