What are your least favorite episodes of star trek? For me it’s when the preachiness gets too extreme;
The Mark of Gideon (TOS): where they go to a planet where no one is willing to have an abortion, because they’re apparently space Christians, and as a result their planet is one giant mass of people and they infect kirk with a virus to kill off the population.
The Neutral Zone (TNG): where they uncover a space pod with frozen humans from the 20th century and Picard goes off on why capitalism is evil.
Notable mentions include Code of Honor(TNG) and pretty much anything from season one TNG.