I find that quite a few shows that don't make it to a sophomore season (or even have a full run of their first season) tend to be pretty high quality.
From a police procedural point of view, while "The Wire" won universal acclaim, it wouldn't have existed if not for its predecessor, "Homicide: Life On The Streets." This show was from the same creator, also set in Baltimore, and featured an amazing ensemble cast headed by Andre Braugher, anchored by the recently departed Yaphet Kotto, and filled out by the likes of Melissa Leo, Richard Belzer, and Ned Beatty. If you can find it streaming somewhere, the first season features an arc about a murdered girl named Adena Watson with writing, direction, and acting of a calibre rarely seen on TV.
From a serial drama standpoint, "Terriers." This is a serialized comic drama starring the criminally underrated Donal Logue, as a private investigator. It's not unlike "Breaking Bad" as done by the Coen Brothers.
From a scifi standpoint, I'm probably alone in this but "Alien3." I actually liked it. I enjoyed the way that Charles Dance's character mirrors that of Dallas - the supposed protagonist who gets killed at the midpoint. And while it is a very slow burn, especially when compared to a James Cameron shoot 'em up, it provides a way to end both Ripley's and the xenomorph's story the way it really should end.
And, for the greatest movie that should be terrible but, instead, is great, well the answer is simple: Star Wars.
An homage to old Buster Crabbe serials that is passably directed using a corny and clunky script, starring an unknown actor of middling talent, backed up by a great actor who was only in it for the paycheck and an old B-horror movie star hamming up his lines, all in service of a glorified fairy tale about a farm-boy saving a princess from the clutches of an evil wizard, where fully half of the dialogue is overdubbed and you can only tell who is speaking by their gesticulating, and with a half-baked story structure that had to be salvaged in the editing room.
Star Wars should not work.