Answer:
Un hotel de cinco estrellas es mejor que un hotel de tres estrellas.
Explanation:
Un hotel de cinco estrellas es mejor que un hotel de tres estrellas. This is a comparison. In English it would be: A five stars hotel is better than a three stars hotel. "Mejor" can be both an adverb or an adjective. In this case it works as an adjective. It's irregular, it comes from "bueno". If it was regular the comparative would be "más bueno", but that's replaced by simply "mejor". Using "más bueno" is grammatically incorrect.
