In order: Horror, Sci-Fi, and Mystery. I do like Fantasy, but it's too wide a genre for me to vote for (there's a lot of fantasy I don't care for). I'm more into horror and sci-fi myself, I love spooky things. I love speculative fiction, too, I love how sci-fi speculates on where we'll be going and what the future will be like. I especially love the nature of fear, I love the analyze why something scares us and what it means. That's why I love horror.
Also, there's this whole big theory of thanatos in horror that I won't bore you with but it's a big factor in why I love the genre XD
Stephen King has a nice foreward in one of his short story books that is a good one-sentence go on the subject:
And the great appeal of horror fiction through the ages is that it serves as a rehearsal for our own deaths.
As for mystery, well I picked that because I like True Crime. Granted, that would be non-fiction, but I don't like most non-fiction. Mystery tends to be a bit of both so I let it count for the True Crime genre.