i like comments where someone talks about a certain aspect of my writing that they really like, or points out certain lines/scenes that worked well and WHY they worked well.

my favorite comment was when someone described my writing style as "hypnotic." they said that it made them feel completely submerged and in a zen-like sort of trance... i actually tried really hard to achieve that affect in the story they commented on, so it was so great to hear that it got across. :3