When you can't find great stories because the fanbase of the dedicated site finds most of the stories on it, a Masterpiece.
The "If you have nothing positive to say, don't post it." mentality is a great contributor to the problem. (And the ability to delete negative reviews from the Author himself)
Except for SciFi/Space Opera, I don't have a favorite genre. I will read something that has an interesting description or is recommended from other people.
So when I read a really good MindControl story, I search for other entries in the genre. But good luck finding something on mcstories or other dedicated sites. Even if the search is passable, the rating or reviews are mostly useless. Everything is the best thing since sliced bread.
I am not a big Superheroes fan but after reading "Worm", I tried to find other similar stories (excluding the same author) .... Yeah, not so much luck in that. Even the Webfictionguide site, that should help with such things is mostly useless, because it is a popularity contest pandering to only a few genres and anything that is a constant serial gets always the top spot, regardless of quality.
SoL is more devise but also has some specific genres that get their fair share of fanbase boosting. Like CoA, DoOver and SciFi.