What to choose to play as black if you play King's Indian Attack as white? I am around 1700 - 1800 player on chess.com, mainly playing 3+2 and 5+5 games and as white I always play KIA, but what I have noticed recently is that with white my score is much better that as black - with white I have 40 victories more than losses, but with black I have only 8 victories more than losses.

So, I was wondering what opening one should play with black if he plays KIA as white?

I have tried French, Sicilian Kan and Pirc, and maybe I had the most success with Kan, but again it is nowhere near as good as my performance with white.
The King's Indian Attack isn't called the King's Indian Attack for nothing; it's White's version of the King's Indian Defense which is an opening for Black, characterized by the moves 1. d4 Nf6 2. c4 g6, and Black intends to follow up with Bg7, d6, castling kingside and either c5 or e5. So you should get a structure you're familiar with, although the precise moves may be different.

You can't really play the KID against 1. e4, so you'd have to opt for the Modern Defense, or the Pirc you already mentioned. If you're attracted to the setup with g6 and Bg7, the Sicilian Dragon would also be an option.


  but what I have noticed recently is that with white my score is much better that as black - with white I have 40 victories more than loses, but with black I have only 8 victories more than losses.


Depending on the strength of your opponents and the number of games you play, this can be quite normal. By moving first, White has a slight advantage and (at all levels of play) this implies players score better with White than with Black. I wouldn't really worry about it for now.