I thought I'd refresh my thoughts on this franchise...
Do you like it? Why do you like it? How long how have you liked it?
Sure do. KOF is one of my favorite series because it has a simple-yet-intricate storyline with the multiple teams involved. Seeing how the teams and individual members of them get involved in the tournament makes for an interesting collage of characters and personalities clashing together. It also helps a lot that there's a solid fighting gameplay system in the games that I play. I started liking it the moment I got to really play KOF98...back in 2005. (Yes I know I'm late to the party---)
What's your favourite game?
KOFXI. Great value, great cast, great gameplay. And there's a deep color edit mode. That keeps me entertained when I have time to spare.
What's your favourite character? Who are you best with?
Shingo Yabuki, by far. I don't know who I'm really "best" with though. I'm honestly not great at all in this franchise gameplay-wise at the end of the day.
What's your favourite team? Do you pick the game defaults? How has your team changed over the years?
Game defaults? There's a reason "Team Edit" exists in KOF! That said, my team usually has Shingo and whoever I like playing as in that particular game. In 2003, it was Shingo/Malin and either King or Hinako. In XI, it's Shingo, and any duo combination of Duck King, Vanessa, Iori, K', Malin, and Clark Still.
Which hero is the best? Which storyline is the best?
Personally, I like K' best as the "hero" character. He's someone who because of circumstance gets dragged into the KOF scene, and while he'd rather not have anything to do with it, he has no choice but to participate with whoever is teamed up with him. His general social awkwardness (i.e. anti-social loner) brings out his disdain towards KOF, which I thought was a nice touch. As for storyline, the Ash saga was the most engaging for me, especially with that surprise ending. I wouldn't have predicted Ash doing what he did in the end when 2003 first came out, that's for sure. Personally though, the best storylines for me are the ones not neccesarily revolving around the main story arc. I like reading about Shingo's antics with trying to team up with his idol Kyo and the rest of Team Japan. Or Mai trying desperately to be on whatever team Andy is on (and failing miserably more often than not). Or Kensou trying so hard to win Athena's affections, yet completely fail to even get her to notice.