I only give 5 star ratings. If I don't like a story enough to do that, I don't bother voting. I probably didn't even finish reading it.
I sometimes give "Pro" ratings in comments. I give these based on how a story rates compared to my favorite professional authors. (Who are, if you care, Lois McMaster Bujold, Dorothy Sayers, Nevil Shute, John D. McDonald, Fr. Andrew Greeley, etc.)
I like stories about good people trying hard to do good things. If they're fighting against someone else instead of themselves or the universe in general, I want the villains to be consistent with some belief structure. I prefer that belief structure to not be simple greed, but if they show some smarts, I can enjoy that. Stupid villains turn me off.
I want the universe to mostly make sense. If a character abruptly stops his/her car on the road, I want an explanation of why no one crashed into them. If a character screams, presumably in ecstasy, I want some explanation of why the cops don't show up ten minutes later. I want things to be easy for the heros / heroines, but not too easy. They can make lots of money, but not without working hard and having a few bumps along the way. I want the story to show other people around when the characters do something in public. Adding landing gear to a spaceship near the end of a story when it has never landed before makes me tune out.
I want good grammar, correct spelling, and good copy-editing. Every time I see "discrete" describing how non-nosy someone is, I bounce out of the story and have to work to get back into it. Seeing "your" used as a verb phrase makes it likely that I won't bother working to get back in.
I love dialog, especially good dialog. I'm still chuckling over something that HLD wrote in Lost Love (http://www.literotica.com/stories/showstory.php?id=158358) describing two kids falling in love by having their fathers make bets on how many (or few) months until the wedding. He did it in eight phrases, with only one of them a complete sentence.
