I usually use 1st. But other times I will use a mixture of 1st and 2nd. 3rd Ed is totally stupid.. changed AC, changed a lot of stuff.

Now that HASBRO owns D&D, I guess they think they need to make it easier to understand or something..
SOME things in 3rd Ed are ok, but I still have my 1st Ed DM book, and use it most..
Ziroc