I chose the one game that has always haunted / intrigued me the most, GDW's Twilight: 2000.
You see, like many of us grognards, I grew up in the 1970s and 1980s; I vividly remember the Reagan years, the concept of "Mutually Assured Destruction (MAD)," and watching The Day After on prime-time TV with my family. So post-apocalyptic futures did not seem so fantastical (or wacky) to me as they might to some; I genuinely feared the possibility of nuclear holocaust during my junior-high and high school years. So much as I loved Gamma World --and much as I totally enjoy playing Mutant Future today -- I guess I always saw the post-apocalypse as a pretty dark and grim place, a la movies like Mad Max 2: The Road Warrior and the highly militaristic RPG Twilight: 2000.
Then, lo and behold, Joe at Greyhawk Grognard called my attention to a pdf sale at Drive-Thru RPG on the Twilight 2013 Bundle! For a mere $10 I could obtain pdfs of ALL the current Twilight: 2013 products released by 93 Games Studio!! I could not resist. Now, many joyous downloads later, I am one step closer to my Open Friday wish coming true. . .
(And while I was scouting Noble Knight for Twilight: 2000 box cover images, I noticed that they have the first edition of the game available for a very reasonable price too. . . . does it never end?)