'The Counter-Clock Incident'
The last episode was one of the best animated ones. The ending is quite well done. Sarah April's last words (the last line spoken in the show) are somewhat metaphorical. She says "it gave all of us a second life". I've always thought of this line as actually referring to the animated series which literally gave TOS and the characters a "second life". Remember this made in 1974 when there wasn't any hopes for a new live action Trek in the future.
"A voice from behind me reminds me. Spread out your wings you are an angel."