I don't think you'll be disappointed. The Monk is spectacularly vile, especially for its day and age. Otranto is much slower, but it's fascinating to see how it and Northanger Abbey by Jane Austin pretty much laid the foundation for what became the Gothic novels of the 20th century. :)
I've not read the following:
Of these, I'm most intrigued by The Monk.
I don't think you'll be disappointed. The Monk is spectacularly vile, especially for its day and age. Otranto is much slower, but it's fascinating to see how it and Northanger Abbey by Jane Austin pretty much laid the foundation for what became the Gothic novels of the 20th century. :)