From my own personal experience with the King's Gambit, I have come to the conclusion that the Fischer Variation of the King Knight's Gambit Accepted is the best variation for Black. Here's an example of a game where I beat a player whose rating is more than 200 points higher than mine. While this game started as a Bishop's Gambit, White eventually moved his Knight to f3 thus transposing into the King Knight's Gambit. I therefore recommend making the Fischer move d6 in both the Knight's Gambit and the Bishop's Gambit. I especially like the brilliant--I just love patting myself on the back--Rook sacrifice on Black's 23rd move that brings home the bacon.