Here's a start.
I love characters that are full of feeling they can't express. Inarticulate fury, tongue-tied infatuation, thoughtless, unexamined devotion--all of them fascinate me.
I love plots with a real sense of mystery to them. Not just "Who killed the vicar?" but a real sense of "Wtf is going on here?"
I love story elements that surprise me. I don't want the same old mopey nightclub vampires. I don't want the same old spaceship battles. Which is not to say that I play originality uber alles. I'm not a novelty-seeker for novelty's sake. But I do like seeing the unexpected.
I love stories that go there. If the characters are looking for the magical doohickey, I want them to find it quickly. I want them to reveal the purpose of the mysterious space object. Show beloved heroes dying in battle. Uncover the killer. Find the treasure. Then I want to know what happens next.
I love characters who do the natural, unexpected thing.
I hate hypocritical characters--Humans can't be trusted with this power! We must kill anyone who finds out about it! Unless it's the protagonist we're talking about.
I can't stand characters who act in very! dramatic! ways! that don't ring true.
I hate fakey violence. Werewolves don't throw people--they chew them to pieces. A pistol-whipped old man doesn't sit up five minutes after and have a sensible conversation about it. With a bag of frozen peas on his head (unless the whipping was administered by his even older mother or possible Mr. Burns).
Here's something else I hate: Supporting character withholds information that would solve the plot in 45 pages for no good reason at all... or just because he's a dick.
I'm sure I could come up with more if I wanted to blow off my whole work day, but that's a decent list.
How about you? Do you have a list of things you love and hate?