FFC and the ODD supplement Blackmoor, with very heavy emphasis on the former.

Temple of the Frog (from Supplent II Blackmoor) is one of the first adventures that I ever played in. My friend got OD&D for Christmas in '75 along with the supplements and we had to figure out how to play in a hurry and without anyone to teach us, since no one else I knew had ever heard of the game. Since we didn't have access to any modules at the time, we first played with the sample dungeon level in book III and our second adventure was TotF.

I was a big Judges' Guild supporter (and subscriber) from early on, and often visited Decatur, IL where they had a store, so I owned pretty much all of the early JG products. This meant that I discovered FFC really early in my gaming life as well.

Part of my love for Blackmoor stems from the fact that I discovered it (and Wilderlands campaign) before I found Greyhawk. Back then Dave was my hero since he had such cool ideas, although I've grown to admire both Dave and Gary since then. (And of course have expanded my "D&D immortals" roster somewhat to include Bob Bledsaw, Rob Kuntz, and others of that era.)

I wasn't really "into" B/X when it came out and was slow to find the DA modules. I think I ended up buying them in the early 1990's or so. They didn't have the same feel to them, perhaps because the rules were more refined by that point in the evolution of D&D. I still prefer a "loose" rules system where the game is more important than the actual rules, and the FFC is to this day one of my favorite RPG books of all time.

I bought all of the d20 Blackmoor stuff, mostly out of loyalty to Dave and to support any product line that he was associated with, but I'll confess that the d20 material just doens't have that spark for me that the older books have. I also bought the 4E book to be complete, but have hardly ever cracked it open.

So, in my biased viewpoint, Blackmoor becomes more "canon" as it gets closer to the original source material. The Twin City version would be the ultimate Blackmoor for me, closely followed by the Supplement II / FFC version, then the DA modules, then 3E stuff is a ways back, and finally 4E at the bottom. I know that others view things very differently (cough ... Havard ... cough) and that's fine, but I know what I like. 8)