Was The Visitor, the episode, Trek? Absolutely. It had all of the above. But, what is it remembered for? How it made us feel at the end. That, while really good, is not that Trekish. And when it's up against all these other episodes, that's enough to put it down.
Well, by that reasoning, Star Trek II isn't Trekish. It's remembered for killing Spock and how the audience felt at the end.
The City on the Edge of Forever would also apply.