Gaston is the antagonist in the movie, Monsieur D'Arque is just a supporting character/minor role.

Beast wasn't an evil because he's just cast into curse.

^^Yeah, I know that Beast isn't evil, but I know some who think Gaston isn't really much of a villain, and that D'Arque or the Enchantress are villains.

Mosieur D'Arque is only introduced as a character because Gaston paid him to get rid of Maurice.
The Beast isn't evil at all, just bad-tempered.
The Enchantress can be considered an antagonist, but she isn't the main one, because she doesn't oppose Belle, the protagonist.
Therefore, by default and due to characteristics of his own, Gaston is the villain

What Flutey_Girl96 said

Flutey_Girl96 pretty much said it all.

I just wonder what would have happened if the prince wasn't turned into a beast....

Yeah what Flutey_Girl96 said

10 points for Flutey_Girl96!

The Beast would be one awesome villain. He really is terrifying at first!

I don't think that The Enchantress should be on the list, she gave the prince what he deserve.

^ did she give the servants what they deserve? Chip??

Is this even a question? Definitely him. Beast isn't evil, he just has bad attitude and short-temper. Monsieur D'Arque is more like minor antagonist for me, as he only oppose Maurice. The Enchantress is a minor character who give the big influence of the story.

I dislike the Beast but Gaston is worse. It's undeniable to me. However, I don't think that Beast should be praised for being better than Gaston.