I have read Lord of the Ring 4 times. Although I found it slow too the first times (first time I read it I skipped almost half of the first book), I must say I liked it as it is important for the atmosphere of the books. I wouldn't take any risk in telling wich book in general is the best, but I'm rather confident that the Lord of the Ring is among the best. I thought that long before it was even planned to make a movie on it, and of course I still think it.
Among the best books in my opinion are also the 6 books of
Dune by
Frank Herbert. Prequels and sequels by
Brian Herbert (his son), although good, aren't as good as the original.
I plan to read Harry Potter someday, but I still have to finish reading Dune for the 5th time, reading all books by Herbert and Brian Herbert from first to last in story chronological order, as well as the ~15 Starwars books that I haven't read yet

The real sign that someone has become a fanatic is that he completely loses his sense of humor about some important facet of his life. When humor goes, it means he's lost his perspective.
Wedge Antilles
Star Wars - Exile