Do you mean:
* "What is more popular, Lord of the Rings or...?" - In this case, please finish the sentence with another book, movie, or other subject to compare it to Lord of the Rings.
* "What is more popular, Lord of the Rings or The Lord of the Rings?" - This is a bit of a trick question. The Lord of the Rings is a single, large book, while "The Lord of the Rings" refers to the entire franchise including the books, movies, games, etc.
Once you clarify your question, I can help you figure out which is more popular!