These books were published 150 years ago. They're supposed to have great literary value
Examples: Pride and Prejudice, Oliver Twist, The Adventures of Huckleberry Finn
Bought by: Mostly high school students using them for book reports
Authors: They're all dead. Good luck getting a reply to your fanmail.
Analysis: Since they're taught in classrooms, you can find hundreds of critical analysis essays. Oh, and the teaching guides. No need to look for themes or symbolism. It's already been found. Analysis mostly consists of theme and rhetorical strategies.
2. "Normal" books
Examples: Well, anything
Bought by: A decent number of people
Authors: Still alive. They promote their books through social media. They'll personally reply to email, tweets, and blog comments. When they release a new book you can probably win one in a giveaway. Only 23 other people entered, so you've got a good chance.
Analysis: You can find reviews in newspapers. Amateur critics, like book bloggers, post their rants online. Analysis mostly consists "Is this a good book or a bad book?" debates.
These are the hugely popular books. The ones that stay on the New York Times Bestseller list for 62 weeks. The ones that turn into movies.
Examples: Harry Potter, Hunger Games, Lord of the Rings
Bought by: Everyone. You can have a conversation about the characters and assume everyone in the room knows who you're talking about.
Authors: Usually still alive but too busy to talk to you. If you're lucky, you can meet them at a convention and get a quick autograph.
Analysis: More thorough than either of the other book types. Millions of people go online to argue about their interpretation of the books. Answer a simple question like "Who's the best character?" and you could get hate mail. Most of the analysis concerns plot, characters, foreshadowing, and world building (setting).
Normal books are supposed to be inferior to fandom builders because they don't have as many readers. Fandom books are supposed to be inferior to classics because they haven't survived the tests of time yet. And classics are supposed to be inferior to normal books because they're not "accessible" enough for the casual reader.
Can't we all just get along?
My personal favorite are the normal books, though I dabble in the others as well. I can't reference them in an essay or in casual conversation.
Each has their merit. Normal books make up most of the literature world. Fandoms rule the internet. As a result, people learn about them secondhand. I've only read 15 of the 28 books shown in that picture but I can give you a basic description of all of them. And classics? These all started out as normal, grew to fandom proportions, and then lived on through time.
There's room in the world for all types of book. Why argue about which one is the best?