Even though this wasn't my introduction to the game, even though this wasn't my first D&D book, even though NOW I play exclusively B/X D&D...this is my book.
It may have to do with coveting this book for so long as a kid (my friend owned it and I did not for probably a year...even though I was our group's Dungeon Master)...or maybe because, once I did own a copy, I carried it with me for years. Even after 2nd edition came out, I DID start/run a couple D&D games...and it was always 1st edition AD&D...and this was always my tome of choice.
Even though I owned TWO DMGs (including the 1985 re-print cover), this is the one to which I always defaulted. For whatever reason, this is the image that's been seared on soul...despite preferring other systems...and even other cover pieces!...intellectually. This is the book that sings to me, for whatever reason.
But, hey...you asked!