Three come to mind
1) 1984. Surprisingly, not so much for political reasons as much as for the realization that everyone is frail, weak, corruptable, and worthy of protection.
2) Terry Pratchetts, "Discworld" books at large. Sure, there funny, but a lot of them will surprise you, and come at you from outta nowhere with something incredibly touching. Anything with Sam Vimes, Granny Weatherwax, and Tiffany Aching come to mind.
3) The D+D Players handbooks from the various editions. Seriously, what other book has inspired such an awe-inspiring number of hours in reading, contemplation, and interaction, or created so many heroes, villains, characters, and settings. I bet that even as video gamers, our lives would be quite a bit different without those humble books.