Uhh... I have no idea tbh how to answer this question, how do i pick a favorite book? idk
But ig here are a few of the book(series that i really enjoyed)

Warrior cats (was one of my childhood book series)
Max Frei(Really interesting fantasy book series, tho most books are only available in Russian)
H.P.Lovecraft in general, love his works
Hitchhikers guide to the galaxy, very fun and awesome and great