SF debris did something similar with another "weird science" song, though I'm not sure who sang this one. He has an even bigger axe to grind against Janeway than I do though. http://blip.tv/sf-debris-opinionated-reviews/tuvix-coda-6054777
Most mediocre....hmmm. I'll go with "Tattoo" and "The Cloud". "Tattoo"...I think I have never ever rewatched? And "The Cloud"...other than Chakotay showing Janeway her animal guide and Janeway's famous quote "There's coffee in that nebula!", pretty mediocre episode. There are a few other Season 1 / Season 2 episodes I can think of as well, like "Cathexis".
For my, it's bride of chaotica (or something). I know it was on the holodeck and it was in black in white. I remember I didn't like it. I don't remember why.
There were some alright and even a few good ones, though the great deal of meh and downright crap episodes far outweigh all of them.