I've not used it a single day, sir. I swear I haven't. Double swears it!
ChessBase Chess Opening Encyclopedia

I have an older version, I think it is monographs taken from the issues of ChessBase Magazine. I would look at chesspublishing.com if you want something more like MCO.

Hello Everyone,
These are some free resources, please see below:
https://www.chesspublishing.com/content/
https://www.365chess.com/opening.php
Best Regards.
Curious what you all think. I always liked the Modern Chess Opening books, I think 12th edition is my favorite as it would explain a bit about what that opening attempts to do, how it favors or disfavors a particular color. I am thinking about buying the new ChessBase 2020 Encyclopedia. I wish it was for Mac, but I can put on my pc laptop if needed. I am interested in your take on this if anyone has used it.
Thank you all!