An unexpected winner that I like quite a bit! I almost eliminated "Amok Time" several turns ago, so I also prefer "A Time To Stand."
Adding it to the master winners list below. DS9 and TNG, now tied for 5 wins each...
INTRO OF RECURRING ALIEN ANTAGONISTS: TOS, Season 1: "Balance Of Terror"
ROMULANS: TOS, Season 1: "Balance Of Terror"
TIME TRAVEL/ANOMALY/LOOP: TAS, Season 1: "Yesteryear"
TRIP TO EARTH'S PAST: TOS Feature: "Star Trek IV: The Voyage Home"
ALIEN ILLUSION: TNG, Season 3: "The Survivors"
KLINGONS: TNG, Season 3: "Sins Of The Father"
BORG: TNG, Season 3: "Best Of Both Worlds I"
MAQUIS: TNG, Season 7: "Preemptive Strike"
Q: TNG, Season 7: "All Good Things"
CARDASSIANS: DS9, Season 3: "Improbable Cause"
FERENGI: DS9, Season 3: "Family Business"
IT'S HAPPENING INSIDE MY MIND: DS9, Season 4: “Hard Time”
2-HOUR/2-PARTER: DS9, Season 5: "In Purgatory's Shadow/By Inferno's Light"
SEASON PREMIERE: DS9, Season 6: "A Time To Stand"
HOLODECK: VOY, Season 3: "Worst Case Scenario"
MIRROR UNIVERSE: ENT, Season 4: "In A Mirror, Darkly, Part I"
SECTION 31: DIS, Season 2: "Such Sweet Sorrow, Part 2"
COUPLE: Sarek/Amanda
Thanks for playing all! I'll have "The Least Disliked Season Finale" up in a day or two...