One opinion I found on what makes a book great:
-Is contemporary in any time and place because it deals with human nature.
- Is indefinitely re-readable because we can always learn more from it.
- Is most strongly connected to the Great Ideas and thereby to all the other Great Books.
- To this some would add "and is always over everybody's head all the time." Mortimer Adler
This link is to a list compiled of the greatest books online.
Then I found this from notes from the writing chair that great books have
great characters
great plots
strong sense of setting
real emotion
Theme-- the book must mean something
Strong characters, ones we care about
Takeaway value which means a truth of human nature
Satisfying ending
Good mechanics
Unpredictability
In Summation: "A good book grabs you by the soul without your knowledge. By the time you're in tears or laughing at the top of your lungs at the same time it's too late. You're hooked." Tom Williams
Everyone has seen the lists of the greatest books of all times about which most readers don't agree. I went looking for such a list and found much diversity. There is not one such list. And worse, even when I saw such lists, I realized the books that have been great in my life, they aren't going to be on them.
My goal when I read is to find books that will add an enriching aspect to my life. They likely won't end up on any NYTimes list of best sellers or even classics of all times. There are some books I simply won't read, like The Lovely Bones no matter how much others say it's wonderful (did not watch the movie based on it either). It had a topic that simply doesn't work for my life. I have enough paranoia and worry over my children and grandchildren without feeding it.
Years ago, when I was just entering adulthood, I set out to read all the books by certain authors like Steinbeck and Hemingway. I haven't reread any of them since, but I can say I've never forgotten those stories. Some of them certainly qualify as great like Grapes of Wrath which still speaks to human nature and culture. It wasn't my favorite though of the Steinbecks, that would be Cannery Row with quotes that still stand up like "Being at ease with himself put him at ease with the world." That was a time when I read voraciously. I'd hit the library as soon as a term was over at college, and the librarians would laugh by the stack I'd carry away that they could tell it was a break.
Of more modern authors, I've enjoyed books like A Yellow Raft in Blue Water, The River Why, have read much of what Louise Erdrich, Carolyn Chute, Molly Gloss, Mary Alice Monroe, and Barbara Kingsolver have written. Everything I read doesn't have to have a worthy purpose-- but if it leaves me feeling worse than when I started the book, I sure won't read another book by that author-- and I will be irritated at myself for putting time into it. I also feel no obligation to finish any book I start. The book has to hold my interest and I better like the characters or it'll be history and no guilt. I have all the difficulties in ranch living to not need to purposely give myself more of it in the name of being literary.