These aren't in any particular order; I've pledged my entire book nerd heart to all of them equally. 

The Mistborn Saga (legitimately perfect)

Dune (timeless)

The Pandava Quintet, a.k.a the Aru Shah series (the best Rick Riordan Presents in existence)

The Nevermoor series (my comfort series)

Wings of Fire (even better than it seems)

The Six of Crows duology (so freaking good)

Hamlet (Hamratio forever! also we do not talk about the ending)

Oh no. This CAN'T be good! I have forgotten to put:

The Phantom Tollbooth by Norton Juster!!!!!!!!!!

It's so good! :D

*quietly* (maybe I overdid it there...) 

I also like The War That Saved My Life and the Vanderbeekers books, Lexi!

Inkheart

The Pear Affair

The Keeper of the Lost Cities Series

Dead End In Norvelt

Up A Road Slowly

Fighting Words  

Bridge to Terabithia 

39 Clues series

Lord of the Rings series

The Hobbit

Percy Jackson series

Heroes of Olympus series 

Kane Chronicles series 

Keeper of the Lost Cities series 

Harry Potter

Percy Jackson/Heros of Olympus/Trials of Apollo

Magnus Chase and the Gods of Asgard

The Simon Snow Trilogy

Keeper of the Lost  Cities

The Gentleman's Guide to Vice and Virtue

Aru Shah

The Wendsday Wars

The Ballad of Songbirds and Snakes (and the Hunger Games trilogy)

The Girl Who Drank the Moon

The Goose Girl

The Giver quartet

The Phantom Tollbooth

Anything by Roald Dahl

The Bookwanderers 

There's probably more, but my mind is  blanking on them right now!

Keeper of the lost cities

All of the Rick Riordan books

Warriors

Seekers

Wings of Fire

Story theives

Harry Potter

The Casey Grimes sieres

Sisters Grimm

Explorer Academy

and many more

Wings of Fire

Warriors

Wolf-Woman

American Girl

Dear America

Dairy of a Wimpy Kid

Dork Dairies

Animal Ark

Magic Tree House

The Egypt Game

The girl who saved Christmas

How to train your Dragon

Spirit animals

Dragonology

(That all I can think of on the spot, if you never read any of those I think you should! Especially Wolf-Woman! It is my favorite book ever!(besides Wings of Fire))

*excited voice* Read these. Read these, I beg of you. They are all so good! They're also really helpful for writers, because *virtuous voice* writers always ought to read the Very Best.

1. Momo, by Michael Ende. A fascinating story of an Italian girl who saves the world from sinister time-thieves. It's so beautiful. It's one of those books that makes you cry. The characters are wonderful people, and the author's message is so relevant to our times, it's breathtaking. Has anyone on here read it?

2. The Chronicles of Narnia, by C. S. Lewis. I shall direct you to the Chronicles of Narnia thread by Amethyst if you want to find out more about these.

3. David Copperfield, by Charles Dickens. This just has fascinating characters, and so many! It's a whole world of its own, and it gets really interesting even though the plot is simple.

I may post some more later :)

Well, I tend to like older books... here are a few:

The Twilight of Magic, by Hugh Lofting, a fantasy book. If you've ever read Doctor Dolittle, don't think of them when you hear Hugh Lofting - it's very different from his other books, and very, very good, set in medieval England.

The Melendy Quartet and the two Gone-Away books, by Elizabeth Enright. These are absolutely wonderful!!!! Although they're set years and years ago, most of the things in them are things still entirely relevant today. The Melendy Quartet is about four children and their adventures; Gone-Away Lake and Return to Gone-Away are about Portia and her cousin Julian, who discover an old town on the edge of a marsh and two people who live in it.

Cherry Ames, by Helen Wells: A series. I think they're extremely hard to find, but they, too, are wonderful. They're about a nurse who lives during the Second World War. When I heard about them, I thought, "Those can't be interesting. What's interesting about a nurse's life?" but they're very interesting, and the characters in them are charismatic, nice... The later books, from Cherry Ames, Visiting Nurse onward, aren't so good, though.

Actually - I've thought of several more books I love.

The Bronze Bow, by Elizabeth George Speare. This book is wonderful! I'll try not to go on too much, but it's vivid, inspiring, exciting, satisfying... Please read it!

The Eagle of the Ninth, by Rosemary Sutcliff. This is about an ancient Roman (I don't mean he's old, I mean he's from Ancient Rome, not modern Rome) who looks for the lost Eagle of the Ninth Legion.

The Chronicles of Narnia, by C. S. Lewis. I know these have been mentioned before, but they really are among my favorite books. Several CBers have complained that many fantasy books aren't good, and I agree... these are really beautiful, exquisite, magical stories.

The Search for Delicious, by Natalie Babbit. Also fantasy, with a clever theme and lovely imagery and characters.

I suppose I really must stop there, or I'll go on forever - but I hope you'll read some of these books!

time to update my list:

Wings of Fire  by Tui T. Sutherland

the Wingfeather Saga  by Andrew Peterson

the Skyward series  by Brandon Sanderson

the Reckoners series  by Brandon Sanderson

Harry Potter  by J. K. Rowling

Insignificant Events in the Life of a Cactus  by Dusti Bowling

Endling  by Katherine Applegate

Warriors  by Erin Hunter