Beauty is very subjective and very much in the eye of the beholder. They're both supposed to be beautiful in very different ways. The Evil Queen is more mature and regal looking (Sometimes even sensual) while Snow White is more innocent and natural looking. There are going to be people who will think The Evil Queen is more beautiful no matter how drop dead the actress that plays Snow White is and vise-versa. Snow White is also considered the fairest because of how her beauty is not only better than The Evil Queen's from the outside but from the inside. Jealousy, vanity, envy, and cruelty can corrupt one. As long as both actresses are beautiful and represent the type of beauty their character is supposed to represent, that's what matters.

I like it when its more or less even. I always liked to think of the Queen as a very dark, sullen, elegant beauty and Snow as a gentle, soft, radiant beauty.

Referred to the whole story, I think so.
But I don't mind if Queen was prettier than Snow. It happens between Kristen Stewart and Charlize Theron but it doesn't matter. Like KataraLover said beauty is very subjective.

In addition to what you said about beauty being subjective, Katara, I think it raises an interesting question about adaptations and how faithful they are to the original story. If they're going to alter certain aspects of the story to make it new/modern, then it doesn't have to be as faithful to the "fairest of them all" narrative, y'know? No one wants to see the same Snow White tale told exactly the same way over and over again, and I think film directors can kind of play around with that when casting and have some freedom.

Yes because it wouldn't make sense for the Queen to be envious of somebody who's beauty is inferior to hers.