In thinking about the possible genres this novel fits into, I think the clearest and best fit is the Gothic genre. Gothic blends horror and romance, and we definitely have that here.
In reading about the Invasion Novel, it seems to also be a valid reading. Dracula can been seen as an outside force invading England for the purpose of a hostile take-over. Though he is only one “person” and not a whole army, Dracula represents a different culture and way of “life.”
The key element of the Fantastic seems to be a hesitation between believing something is supernatural/dreamt or natural (real and logical in the world of the novel). This genre does not seem to fit Dracula because there is no rational explanation for the events of the novel. While some of the occurrences can be explained, most of the events surrounding the Count have no logical explanation. The characters seem, in the end, to believe that Dracula was a supernatural being, and readers, too, must make draw this conclusion. It is only in the earliest part of the novel that Harker thinks his experience in the castle could have been a dream, but for the other characters, especially Van Helsing, that is never a possibility.