None of them is correct. It is not you that "hits the spot," it's the thing that gives you pleasure that "hits the spot." It usually means a fairly trivial pleasure, like a cup of coffee. And it means that it seems better than usual, you are surprised at how good it seems, because it is just what you needed.
For example, suppose you are hungry and you don't realize it. Then you eat a sandwich and say "Boy, did that ever hit the spot."
Or, it is a very hot summer day and you are sweating, and someone says "Would you like a glass of iced tea?" And you say "Yes, please, that would really hit the spot." It isn't just good; because it is a hot day, it is wonderful, it "hits the spot."
I don't think you would ever use it to describe sex. "To hit the spot" is innocent, it's not taboo, it's not usually sexual innuendo (although there is an erogenous area in women that is called "the G-spot.")