lotr is to modern fantasy what dragon ball is to modern shonen. It invented or re-popularized nearly all the common tropes you find today.
It also has one of the most impressive mythologies of any fantasy series ever, but the books are prone to over-indulge in somewhat meaningless details as a result. Its hard for me to get through the books, especially Return of the King. The second half of fellowship and the two towers are really great though. The Hobbit is the best book Tolkein wrote imo