What is your favorite TV show that only lasted one season?
I can only think of one recent one. Orphan Black: Echoes. I was sort of getting into it. I never realized until just now that it was a sequel to another Sci-Fi show called Orphan Black.
However, my very favorite show that was cancelled that really doesn't fit this category because it lasted longer than one year, was Greatest American Hero. I just thought it was a very unique premise for a show: An ordinary schoolteacher gets a close encounter of the third kind, during which they leave him a suit with magical powers and a set of instructions on how to use it. He loses the instructions, so he's not quite sure what the suit can do or how to use it properly, leading to all sorts of high jinks and surprises. The casting of Robert Culp as the very serious Alpha male FBI agent who thought he was in control of our "hero," played by William Katt, was inspired. Besides, Connie Sellecca was in it and it had the best theme song ever. "Believe it or Not" became a hit, reaching No. 2 on the Billboard chart. It's unfathomable to me how it only last three seasons.
Another that was cancelled way too soon for my liking was Battlestar Gallactica, which lasted four seasons. It was better than Star Trek, IMO. The rumored reason they cancelled it was because it cost too much to produce because of all the elaborate sets. I find that hard to believe (once you build a set, you don't have to build it for every show) but that was the rumor at the time.