The characters are a huge part of it for me too. I want them to be unique (but not over the top, unless it's a comedy, I suppose), I want them to be interesting, and I want their actions and motives to be in line with their background and personality.
Other than that, it's anticipation. I need something to look forward to. Whether it's the resolution to a conflict, the development of a relationship, the build up to a dramatic fight sequence, the turning point in a character's development, etc. It has to be done in a way that makes me excited to see the progression. In general, I prefer stories that don't just build up to one big thing (the major conflict, the big love confession, w/e), but build up to many things, milestones I guess.