I love "Miri", "The Conscience of the King", and "Mudd's Women", and was stunned to learn that some in this community do not.
I love those three episodes, too. There's lots to love in them, actually:
"Miri" --
Exterior filming (OK, it's the backlot, but it's still outdoors)
Yeoman Rand
Kim Darby and Michael J. Pollard, both memorable
A race-against-the-clock story (I love those)
Spock's "beakerful of death" line -- classic
"The Conscience of the King" --
Fantastic script loaded with excellent dialogue
Inspired direction by Gerd Oswald
Only time we see the observation deck and the ship's theater
Great performances by Arnold Moss and Barbara Anderson
Shatner's best subtle performance of the entire series (IMHO)
Fine music score by Joseph Mulledore
"Mudd's Women" --
Dreamy early-first-season photography
Karen Steele as Eve
Superb direction by Harvey Hart
Really, all 29 first-season episodes have plenty to commend in them. (Even "The Alternative Factor" has location filming and an intriguing premise.)