Best chess opening? Both black and white...

I mentioned three.

If you think it might help, I could identify older anti-Sicilian books, but they mostly have "Anti-Sicilian" in the title. For example: Anti-Sicilians: A Guide for Black.

http://www.gambitbooks.com/pdfs/Anti-Sicilians_A_Guide_for_Black.pdf

Were you kidnapped by the Illuminati?

Phoeny 

I understand what you are saying completely I was the same way. The first opening I learned was the English opening which is 1.c4 people told me to stop using it and use some of the openings i listed instead. I remember thinking why? I win with it and I memorize the moves and I know the principles. 

however, after trusting the process, I get it because there is a difference between knowing the principles and understanding how they are applied along with the position. in the openings, I listed it is much easier to see what is really going on with position and principles than in the openings you listed.  

Think of it this way say you have a light 2 door coop car it is light easy to handle and good for learning then you have a big uhaul moving truck with very sluggish handling. You have all the moves and principles memorized turn the key turn the wheel left and right gas pedal brake pedal. Both have their purposes and are useful in for different people in different circumstances, however, it is much easier to learn and understand and get a feel and understanding for what you are doing by starting with the coop than the uhaul. You could theoretically start out with the uhaul but you will be driving in 2md gear for a long time and not going anywhere fast.  

the opening i listed are the coop the openings you listed are the uhaul. 

Trust me, stick with the process prescribed in the link I posted and you will learn and progress faster. also, remember tactics tactics tactics!!!

I think it is fairly common to see advice like that quoted in #4, but I think it is considerably less common for it to be claimed that serious negative consequences will come from a failure to follow such advice. Indeed, I would guess that much of the actual negative consequence could be balanced by the enthusiasm one might feel from using an opening that one likes. I would just say to be open to the possibility of change if, at some point, one is no longer happy with one's past choice.

"... You should prepare your repertoire according to your own chess tastes and style. ..." - GM Artur Yusupov (2008)

I fear that you may find that Kotronias presented a lot of moves without much discussion of the reasoning. Here are samples from the five volumes:

https://www.qualitychess.co.uk/ebooks/KotroniasontheKingsIndianFianchettoSystems-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/Kotronias_Mar_del_Plata_One-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/Kotronias_Mar_del_Plata_Two-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/Kotronias_Classical_Systems-excerpt.pdf

https://www.qualitychess.co.uk/ebooks/Kotronias_Samisch_and_Rest-excerpt.pdf

"... [Kotronias on the King's Indian: Volume One] is wonderful, but unbelievably dense and best suited for advanced players who have a lot of time (and a very good memory!). ..." - IM John Watson (2014)

http://theweekinchess.com/john-watson-reviews/john-watson-book-review-113-kings-indian-part-2

For discussion of the reasoning behind individual moves, I think that one might have better luck with something like Starting Out: The King's Indian (2002)

https://web.archive.org/web/20140627055734/http://www.chesscafe.com/text/hansen38.pdf

or Winning Chess Openings (~1999).

https://web.archive.org/web/20140627132508/http://www.chesscafe.com/text/hansen173.pdf

However, both of those books are kinda old. FM Carsten Hansen once (2010) wrote:

"... For inexperienced players, I think the model that bases opening discussions on more or less complete games that are fully annotated, though with a main focus on the opening and early middlegame, is the ideal. ..."

There are two fairly recent books of that sort with discussion of the Queen's Gambit Declined:

First Steps: The Queen's Gambit

https://www.newinchess.com/media/wysiwyg/product_pdf/7652.pdf

The Queen's Gambit Declined: Move by Move

https://www.newinchess.com/media/wysiwyg/product_pdf/7743.pdf

A Houska sample can be seen at:

https://www.newinchess.com/media/wysiwyg/product_pdf/7507.pdf

As you can see, she set out to include "plenty of explanations of ideas and basic principles, along with some new theory", but it does not take very long to get to things like variation B2d.

"... it is arranged in the tradition of a classical opening book – by variations rather than model games. ... Highly recommended for players 2000 on up. ..." - IM John Donaldson (~2015)

http://www.jeremysilman.com/shop/pc/Caro-Kann-The-76p3909.htm

For the model game approach, one could turn to First Steps: Caro-Kann Defence

https://www.newinchess.com/media/wysiwyg/product_pdf/7800.pdf

or Opening Repertoire: ...c6.

https://www.newinchess.com/media/wysiwyg/product_pdf/7673.pdf

Maybe try: The Ruy Lopez: Move by Move (2011)

https://web.archive.org/web/20140627022042/http://www.chesscafe.com/text/hansen153.pdf

or The Ruy Lopez Explained (2005)

https://web.archive.org/web/20140626201436/http://www.chesscafe.com/text/hansen80.pdf

It seems to me that the advice of "News" is somewhat in conflict with what FM Steve Giddins wrote in 2008: "... Overall, I would advise most players to stick to a fairly limited range of openings, and not to worry about learning too much by heart. ..."

One does not need to know about the Giuoco Piano and the Two Knights unless one intends to play for 1 e4 e5 2 Nf3 Nc6 3 Bc4 as White. In that case, one can choose just one of the options (QGA, QGD, Slav) as one's reaction as Black to 1 d4 d5 2 c4.