I treat a moral sense similar to how I'd treat a "yummy" sense. Your nervous system does an evaluation. Sometimes it evaluates as yummy, sometimes as moral.

But the moral sense operates with a different domain and range than yummy, in that it has preferences between behaviors, and preferences between preferences about behaviors,... and implies reward and punishment up the level of abstraction in that scale of preferences.

I opted for Subjectivism as the best match.

Error Theory just seems rather dumb. I think I get the sense in which you mean it, which seems like a valid observation about the error of objectivists, but I think you're mistaking the definition here. It said " moral rightness and wrongness aren't features that exist", but they do, regardless of confusion that moral objectivists may have about them. They exist to you, right?

Non-cognitivism seems like a straw man moral subjectivism. There is a lot more to it than just "boo". There is structure to the behavioral preferences and the resulting behavioral responses.