Since you can choose Calisto as an actual love interest, I wonder how that would turn out? Speculating with just the current known love interests, choosing any of the available girls outside of Calisto seems straightforward enough.
1. Choosing Sharon, the MC gets to keep all of his pets, and toys cause Sharon doesn't seem to mind. Although, that path might lead to some form of conflict with Calisto, and her interests in the MC.
2. Choosing Laurie, Ivy, or Carmen, seems straightforward. They're not power players within this novel. They'll just stick by the MC's side, and follow along. Sharon won't have issues with them, but Callisto will still be a factor to consider.
3. Choosing Calisto, that's where things are not as clear. She's a power player within the story, and she is very controlling. She can either claim the MC for herself, let him be with everyone he desires, or she can just kill everyone associated with the MC. She might even kill the MC herself. Her path seems to have the most twists, and turns because of her mysterious intents, and nature.
4. Choosing the vision girl, just for speculative fun. This option would be well beyond even that of Callisto's path. Will it be like sitting next to god in his throne room, and looking down on everyone else in the vampire world?