"Andymon. A Space Utopia." by Angela and Karlheinz Steinmüller. I found it in the youth-Section of my puplic Library and read it at age 13-15 something and it blew me away. It hit me so hard, i couldn't forget it. Everytime a song from a special Tape that i listened to when reading it, got me massive flashbacks. I bougt it between 30-40 and it hit me again. That is my emotional Gem.

Then some classics like Ender's Game from Orson Scott Card and the Foundation Series from Asimov. Not only the Trilogy but the whole Series is a banger.