It's tied for favorite with me - I love 'em all, really. But I've had many fond memories, both as a kid playing in campaigns long past, and recent memories as I've introduced new faces to the cool parts of AD&D, and rekindled interest among long time gamers in various convention games.
I still have an old three-ring with all my previous AD&D characters in them - Linnaeus the Druid (the most twinked out character I ever owned), and Baxian, Swashbuckler of the Heplahnen Guard (the character I most enjoyed playing), you are both missed, as are the people in the groups we played in.