Let’s compare my Top 10 TOS list…
No one likes the two “children” episodes (“Miri” and “Children Shall Lead”). If I had to do Top 5 I would narrow down to:
“The City on the Edge of Forever” (Joan Collins episode)
“I, Mudd”
“The Trouble With Tribbles”
“Assignment: Earth” (Gary Seven)
“All Our Yesterdays” (Mr. Atoz and Atavrochron episode)
Others mentioned I’ll agree are top 20 at least:
“Dagger of the Mind” (because of the acting of “Van Gelder” and the effects of the mind-emptier).
“The Doomsday Machine” (the acting of Comm. Decker, this one I’ve seen on most people’s Top 10, you have the planet killer giant tubular log thing, some shuttlecraft, and the “tense” music everyone likes).
“Where No Man Has Gone Before” an early one, one of the “gods” episodes, all the “god” episodes I like, another is “Who Mourns for Adonais?” (Apollo episode).
“Shore Leave” I forgot about, that one has a lot going on, Alice in Wonderland episode.
“Balance of Terror” is one of the Romulan episodes, and “Amok Time” is the main Vulcan episode, good if you want the background on the Romulans and Vulcans.
“Piece of the Action” (gangster episode, lots of humor) and “Spectre of the Gun” (OK Corral episode) I like for the same reason, guns and back in time episodes.
Other episodes not mentioned are the Kirk (and crew) vs. computer episodes:
“The Changeling” (‘I am Nomad’ episode)
“The Ultimate Computer” (M-5 episode)
“The Apple” (where its a cult sacrificing to Vaal, which is really a computer)
“Return of the Archons” (Landru who is also really a computer)
There are about 3 or 4 more of these type.
There is also the 2-parter The Menagerie which I put in Top 20 at least, but that’s a 2-parter with scenes from the original pilot (you can see the 1964 pilot “The Cage” in the DVD set, or download with UTorrent).
I can’t think of any I would put as the “worst”, some people say “Spock’s Brain” but I liked how he helps McCoy repair his own brain at the end. Maybe the “Hippie” episode might be the worst (“The Way to Eden”), that one occured just on the ship. The ones just on the Enterprise are normally weaker. Also the ones from the Third Season are probably weaker (due to budget cuts critics say).
Sorry I haven’t watched anything much else except Star Trek T.O.S., and maybe a few of the X-Files episodes in the 1990s. I am not a TV watcher.
Phil P