Dreamies are the villagers people like the most/want the most in their towns. For example, Carmen is my #1 dreamie and it took me a good while to find her, but I didn't give up because my town felt incomplete without her. It is not about being better, it is just personal preference, really. It just so happen that certain villagers are very common dreamies, like Marshal, Zucker, etc.
That person was just asking a question, no need to be rude to them.
Anyways, I am looking for Ken, Jacques and Phoebe. PM me if you have any of them and are interested in selling.