The KOF'94 OST is great, especially "Jungle Bouncer" (Ikari Warriors), "Ne!" (Womens' Team), "Esaka" (Hero Team), Korea's BGM, and Rugal's 2nd BGM. I haven't heard the '94 AST.

KOF'95's OST is consistent in quality with its predecessor. King's Bar has some nice music in this one, and during that stage in the game you'll notice Lucky Glauber in the background playing a harmonica during one part of the song (at least on the MVS).

My favorite '96 tracks are Kyo's BGM (OST & AST), Psycho Soldier (AST), Geese's (Both), Krauser's (Both), and Goenitz's (Both).

1999's BGM is fairly good even if it doesn't touch 94-96. KOF 2000's is okay, but not earth shattering.