Good question. I am interested in good books, too.
My suggestion is 100 Chess Master Trade Secrets https://www.amazon.de/100-Chess-Master-Trade-Secrets/dp/1849941084
Positional chess books for breaking ~1900 fide?
You may find a couple of titles of interest here (toward the end of the article)....
Good Positional Chess, Planning & Strategy Books for Beginners and Beyond...
https://www.chess.com/blog/RussBell/introduction-to-positional-chess-planning-strategy
I haven't played tournaments in a couple of years but I was 1800+ for a while. I feel like I'm better now, let's estimate around 1900+- fide.
I want to improve positionally, learn more advanced concepts and just understand the pieces and setups more. I'm aware of aagard's books but I've heard they're geared towards 2200+ players to improve whereas I'm trying to get there. Is this true?
I've also heard yusupov's books are good but I'm not sure which level they're aimed at. I understand all the basic principles like weaknesses, good/bad pieces, weak squares, doubled/isolated pawns etc. so I don't want to go through that again.
I just want some suggestions. Thanks.