What is the most important quality of Gothic stories?

In gothic stories, or any form of gothic literature and media, there are several factors and qualities that make the story dark and terrifying. The most common among these qualities is the ability to shock and frighten, as well as the ability to create suspense and mystery. The question most people ask is which one makes the story better, and thus more terrifying. Some people prefer the ability to shock and frighten, like in a horror movie when something jumps out of nowhere and scares the viewer. I personally do not care much for this quality, while it is effective to keep the viewer intrigued, the scare goes away almost as quickly as it happens, not exactly creating a long lasting impact. The other quality, the ability to create suspense and mystery, is another favorite among most fans of the gothic genre. I think this is a better quality because of how deep and thought provoking the situation can be. I like the idea of a man slowly slipping into madness thanks to the situation he is in combined with his inner most feelings. This can create a much better lasting impact on the reader or viewer, and I think is something that should be done much more often in gothic literature.