I think Children of Earth (and possibly Miracle Day depending on how this whole thing works out) was it’s prime.
Freefall had the shocking event, but other than “the moment” was formulaic and just sad. And Romano looking up and shouting “nooooooooooooooooooooo” in slo-mo was just cartoonish.
Indeed – I think Torchwood has progressively improved. The first season was pure episodic hijinks. Fun, but shallow and silly. The second season pushed things around a bit more and, I felt, had generally better writing. Children of the Earth was a masterpiece of scifi TV. And I’m liking Miracle Day even more – it doesn’t have the focused pacing of CotE, but I’m really liking the characters, writing, boosted production values, and the very, very cool premise.
The original Battlestar Galactica was never that great to begin with. Galactica 1980 was an abomination. But one episode, “The Return of Starbuck”, was awesome.
The obvious example is “Archie Bunker’s Place” (the lackluster continuation of “All In The Family”) and the episode “The Death of Edith”.