2k1 and 2k3, the two shittiest KOFs made in recent memory, IMHO.
I thought this was "what do you like about KOF".
My favorite kof games are 96, 97, 98, 2k and 2k2. But, to answer the question that I thought was being asked, I'd have to say the gameplay, concept, characters, music, and to a very small degree, the story. So many different fighting styles and character types all joining up to kick each other a new asshole. Plus, it's so cool that the different games go head to head (KOF94 was a dream come true for some people, at the time.... yeah, we had FFS with Ryo in it, but this was so much more!).
Spike