I thought that Mission: Impossible got a lot better after they dumped Steven Hill and hired Peter Graves. I know there are others who feel differently about this, however.
One doper suggested “Felching the Cow,” based on an episode in the first season of the Paris Hilton-Nicole Ritchey show, the name of which escapes me at this moment.
I know Star Trek: Voyager isn’t very popular 'round these parts, but for mine the show really took off with the introduction of 7 of 9. Not just the perve factor
I believe the humour in the Simpsons started to become more sophisticated at series five. I would say the ‘star’ of the show evolved from Bart to Homer during the first few series too. Perhaps someone can pinpoint which episode this began.
I thought that replacing Chevy Chase with Bill Murray was a real step up for “Saturday Night Live”. Of course, the show’s gone through lots of ups and downs since then. Some years were just god-awful.
In comics … sorry, graphic novels … this is called “finding one’s voice”, as in Neil Gaiman “found his voice” in “The Sound of Her Wings” Sandman issue 8.
FWIW, my vote is Star Trek:TNG second season. After Tasha Yar departed, they found their voice. And Taxi found its voice after Bobby left & Jim Ignitowski [sp?] arrived … slowly.