It's probably not controversial to suggest that "Turnabout Intruder" is an abominable send-off for TOS. Similarly, "These Are The Voyages" is... not great, exactly.
If you don't like the finale - or entire final season(s) - of a Star Trek series, what episodes do you think would make good makeshift finales instead?
For TOS, "The Tholian Web" works well - that way, the series ends with Spock and McCoy working together and Kirk coming back to rib them both over it. "The Savage Curtain" works fairly well too; the series ends with Kirk expressing his belief in a better future and his desire to continue the good work of past humanists.
For TNG, "All Good Things" is fine but oddly I always find "Emergence" makes for a fairly sweet finale - the Enterprise-D gives birth to a new lifeform based on the crew's fantasies, and from that it learns compassion and heroism and carries those values forward. Granted, the episode is boring as shit, but thematically it's a good conclusion to the show.
With DS9 you're obviously locked in to the end if you go into the war arc seasons, but if you want to rewatch just the first few seasons, "Explorers" is a fantastic sendoff - Jake and Sisko embracing as the Cardassian government begrudgingly acknowledge the successes of Bajoran culture, which is a situation that will no longer be thematically or logically possible in what the show turns into afterward.
Any others? I suppose Voyager's stuck with "Endgame" (which is fine for what it is), unless you want to awkwardly end with them still trapped in the Delta Quadrant.
The TNG & DS9 finales were great/fine, no need to change. TOS could literally be whatever episode was broadcast the last.
For me of all the finales Endgame hurt the most. Because I liked VOY, and it deserved a much better conclusion to it's premise.
If I could re-do it, I would also involve the Borg.
But I'd have the Borg launch an invasion on Earth. And the Voyager somehow gets dragged along the Borg fleet through the transwarp tunnel & suddenly is in the Alpha quadrant. Now they have to rush to Earth first - and instead of having a peaceful, somber arrival, suddenly everything is hectic, their home itself is threatened, and instead of having a happy reunion, everyone has to scramble to make a plan. Instead of Tom & his father hugging it out, he has to introduce his wife & daughter on battle stations.
And then only after the Borg invasion fleet is defeated, with the VOY crew & Starfleet (Admiral Paris, Troi, Barcley) having successfully worked together - everybody is celebrating the immediate victory, and only then the realisation slowly setting in -
they made it. They're back. The end.
Barring this - and following the threads original rules - VOY's "timeless" (aka "the better Endgame") was also always a great finale, ending on a fantastic positive note.
I've weirdly made my peace with the ENT finale - the amazing two-parter is the "real" finale. And TATV is just a hologram story for Riker, as real as DaVinci on VOY - an artistic recreation of events more than 200 years ago, a commentary how ENT as a television series is also wrong about the future in 100 years.
