The first comic I read was Dr. Strange #2 by Englehart and Brunner, and, as I can still recall pouring over every panel, it shaped the way I appreciate all illustrated books. Also, How To Draw Comics The Marvel Way was one of the most beloved--and compulsively re-read--books of my childhood.
My Marvel and DC collection essentially starts at the Bronze Age. I've been acquiring complete runs of Conan, Red Sonja and other barbarian titles, and if you throw in Wonder Woman's white suit era, Black Widow's stint in Daredevil, a bunch of Man-Bat appearances, Weird Adventure featuring The Spectre, and O'Neill and Kaluta's The Shadow, those shortboxes convert to Bronze right quick! My Copper/Modern collection is mostly the continued sword-and-sorcery character runs mixed with title runs from smaller publishers like First, old and new Valiant, and Dark Horse.