Captain Proton
I firmly believe that it's one of the biggest crimes in television that Captain Proton never got its own spin-off. The other being The Scary Door in Futurama (yes, I know it's a parody of The Twilight Zone, but it could've been marvellous).
I don't even think it would've necessarily mattered if it didn't have Robert Duncan McNeil as Captain Proton. That was Paris playing a holodeck story, so that could be explained by having the actual actor who does it being "replaced" by Paris in Voyager.
However, it would CATEGORICALLY need Martin Rayner and Nicholas Worth as Chaotica and Lonzak. Rayner absolutely killed it as the fiendish Chaotica, and the whole thing was done and scored so well, that it came together beautifully. It would even be in Black & White, with cheesy low budget effects.