I'm rewatching Embarrassing Phases and honestly gotta say,
Frankenstein's monster was a more fitting choice for Logan.
In the original novel, Victor Frankenstein isn't even a doctor. He's a college dropout, who very stupidly decided to play god and try to create life. He never took notes about his experiment, or did any amount of research, the dude literally went graverobbing and decided to create a human being in his college dorm.
And then when the creature turned out to be a little inhuman and scary looking, he immediately abandoned the creature, and decided to mope and moan about the wretched life that he himself had created. He did nothing to stop the creature or protect people from it.
In fact, when he realized that his experiment didn't turn out quite as good as he had hoped, literally the first thing he did was to go and take a nap and let the creature make its way out of the house and cause chaos.
Not to mention, when the creature asked him to create a female creature so it could have some company, instead of simply not giving his new creation reproductive organs, Victor decides to throw a fit at the very last moment because he was scared that the two creatures would reproduce and make monster babies.
This absolutely does not sound like a character Logan would want to dress up as. If he actually met someone like Victor Frankenstein in real life, he would not hesitate to deck them in the jaw full force.
Meanwhile, Frankenstein's monster proved to be not only physically strong but also very intelligent. He quickly learned how to speak, light fire and try to support himself. He learned how to speak French from some books he had found while traveling, and he tried his best to understand and help people. He was curious about the world he was brought into, and was interested in learning more about it. He even tried to reason with his creator, asking him to understand him, only turning "evil" when he truly felt neglected.
This actually has a lot of similarities to Logan who is constantly neglected by Thomas and the other sides. Like the creature, Logan's efforts are ignored and his feelings invalidated. And like the creature, he lashes out when he is repeatedly shut down or overlooked.
While we're on the topic, I do wish Logan had dressed up as the book version of the creature, instead of the pop culture version. In the book, the creature was actually extremely good looking, it was over 6ft and had long luscious hair. Frankenstein had made sure to give it the best features because he wanted to create a perfect human being.
The only problem was that the creature looked a little off, a little uncanny; its skin was pale and yellow (obviously, because it was made from corpses), and it's eyes were also a somewhat unsettling shade of yellow. This is the only reason it is described as ugly and horrendous, mostly by Victor himself.
The creature was not green with bolts on its neck and weird hair. And like I mentioned earlier, it could speak quite eloquently, unlike the pop culture Frankenstein which only communicated in creepy groans.