Well I would have to say that "The Fight" or "End Game" was probably Voyager's worst Episode, my least favorite episode to watch would have to be either "Disease" or "Nightingale". I dispise Harry Kim with passion, and when he back mouths our Captain, I just want to kick him in the butt!!
So Voayger's worst Episode: The Fight
My Least Favorite Episode: Disease
my 2 cents...........