Anyway, I think I could make a kind of a list of top books in certain categories. In the future, if I find this post, I will be able to compare. Might be useful to somebody as well, idk

All books here are very big and very thick, many are series.

• Young adult fantasy (big series)
Leigh Bardugo "Grishaverse"
Brandon Sanderson "Mistborn"
Carlos Zafon "the Shadow of the Wind" (1 book)
Philip Pullman "His dark materials"

• Serious fantasy (big series)
Brandon Sanderson "the Stormlight archive"
Max Fry "the Labirinths of Ekho" (urban fantasy detective, it is basically Harry Potter for adults)
M. and S. Dyachenko "Metamorphoses"

• Fiction
G.D. Roberts "Shantaram"
Guzel Yakhina "Zuleikha opens her eyes"

• Science-fiction (I am not a fan or expert here, though)
Douglas Adams "The Ultimate Hitchhiker’s Guide to the Galaxy"
Frank Herbert "Dune" (series)
David Mitchell "Cloud atlas" (1 novel)

• Detectives, thrillers
Dan Brown "Deception point"
Stieg Larrson "The girl with a dragon tattoo" (3 books)
Steven King "Running man" (novel)
Arthur Conan Doyle and Agatha Christie (everything)

• Classical or nearly classical
Ayn Rand "Atlas shrugged"
Senkevich "Quo vadis"
J. Galsworthy "the Forsyte Saga" (a series)
A. Cronin "The stars look down"
Margaret Mitchell "Gone with the wind"
Leo Tolstoy "War and peace"
George Orwell "1984" and "Animal farm"

Not long ago I realized that it is impossible to answer the quesion "What are you favorite books?" because the books you read at the age of 20 might not impress you as much 10, 15, 20 years later. So, basically you can only say something like "Shantaram is one of the best books, and this opinion was based on my reading tastes, outlook and coordinate system in 2015, and I have no idea if I would love it now or not".

Of course, there are exceptions, but overall this rule rings true.