Mine is definitely Brave New World, by Aldous Huxley.
I first read it when I was 15, and it really resonated with me. The whole concept of a struggle for self-identity in a society where self-identity does not - indeed should not - exist, rising through the normality and standing alone just so you can be the person that you know you need to be, that really spoke to me. The idea that human emotion cannot be held back by technology and the promise for a "perfect world". When our humanity has been taken away, it does not mean that it cannot return.
I also find it interesting to look at Brave New World in the context of a "modern" adaption of the utopian concepts found in Plato's Republic, with the use of technology to theoretically fix a lot of problems as far as the adaption of that type of society goes, such as: dissolution of the family, surrender of the self for the good of society as a whole, acceptance of a pre-determined social and political role that you are born to and die with, and the destruction of art, music, poetry and religion. The idea that technology, created by humans, could be used to strip us of the things that quintessentially make us human is a concept that intrigues me. Is the "perfect" human society really worth it if we cant really define ourselves as human anymore?
Megan