AA50! Clearly! :-D
but I also have a soft spot for the Classic board and the clean generic sculpts that introduced me to this thing in the first place. 80s nostalgia and Revised I suppose, for making me fall back in love with A&A, and for the tank crush, and putting artillery into the mix once and for all.
But the 50th Anniversary edition is my favorite board hands down. The 6 man split with Italy, the 18 vcs, the attempt to include official rules for bonuses and tech, and the box and map design. It was the last board to come with paper money and a full compliment of factory sculpts.
I wish I could get as excited about the tactical theater boards and Global. I bought the 1940 games mainly for the sculpts, and the giant board, but in terms of the gameplay and hours spent playing my heart remains with AA50. Even if China annoys me, its still the best.