Just a simple survey about what makes a great story. If mods can help with a poll that'll be awesome. Of course all are important, but you can only pick one
- Freshness of the plot
- Consistency of the plot
- Depth of the characters
- Impact of player actions
You don't want the same-old-same-old. Enough with the boy-meets-girl-I-am-your-father-the-butler-did-it-happily-ever-after crap that you have been reading forever.
Consistency of the plot
The whole story should be believable and internally consistent. Superman shooting heat rays from his eyes is fine, but Batman shouldn't be able to. No Deus-Ex-Machina-kryptonite-it-was-just-a-dream type of endings.
Depth of the characters
Characters should have some sort of development. Players need to "like" the NPCs. Maybe the NPCs have an interesting quirk, or have cool personalities, or are crucial to the plot, or just plain bad-ass.
Impact of player actions
The players should be able to affect the story. Players want branching storylines with multiple endings that are determined by how they play the game and what choices they make.
The story is only as good as the story teller. A mediocre story can still be great if you get the right actors and writers. You want good voice actors where you can hear the difference between panic and anger. You want good dialogue where characters say things that are consistent with their personality and age.