As someone who has read more than 800 books, as classified on GoodReads, I have definite favorites in each of the genres. Below, please feel free to look into some of my suggestions of some of the best!

Mystery/Thriller

Behind Her Eyes by Sarah Pinborough – One of my favorite endings of all-time!
The One by John Marrs – Unputdownable!! Would you want to know your perfect match if it was scientifically proven to be true?
Verity by Colleen Hoover – I have never read a book faster than I read Verity. It starts with the job offer of a lifetime but chilling realizations quickly begin to spiral spiral.
Horror

Bird Box by Josh Malerman – Malorie is one of the few survivors when terrifying things begin to roam the Earth and drive people mad.
Imaginary Friend by Stephen Chbosky – Full of interesting and well-developed characters, Stephen Chbosky’s wriitng is very reminiscent of Stephen King, which is probably why I loved it!
Pet Semetary by Stephen King – A family moves to a new home where there are many secrets hidden in the pet cemetery in their back yard.
Historical Fiction
The Nightingale by Kristin Hannah – Journeys of two sisters during war.
Before We Were Yours by Lisa Wingate – Inspired by the true story of children being taken from their parents and given up for adoption.

Young Adult
One of Us is Lying by Karen M. McManus – Breakfast Club meets a solid mystery!
Lemony Snicket’s A Series of Unfortunate Events – This is simply such a fun series, and I have read the first ten! I recommend every one of them! Don’t forget to watch the movie after,
Children’s
The Hello, Good-bye Window by Norton Juster – This follows a little girl spending the night with her grandparents.
The Giving Tree by Shel Silverstein – One of the best pieces of literature ever written.
Stick and Stone by Beth Ferry – Ever wonder how Rock, Paper, Scissors started? Hysterical.
General Fiction
The Catcher in the Rye by J.D. Salinger – My favorite since high school, and one of the few books I have read more than five times.
The Seven Husbands of Evelyn Hugo – Which of the seven did Evelyn Hugo really love?