There's no one definitive answer to this question. It depends on your preferences as a reader. Some good titles for romance books include:
-The Notebook
-Gone with the Wind
-Pride and Prejudice
-Sense and Sensibility
-Eternal Sunshine of the Spotless Mind
These are just a few examples. If you're looking for more ideas, try checking out lists of best-selling romance novels or doing a search on Goodreads.