Well, to me, the one that really stands out on that list is “Now and Again”.
It wasn’t even given a 2nd season, and the 1st season finished #1 in it’s time slot almost every week.
Even worse, the 1st season cliffhanger had Eric Close character escape, and takes his family with him. The last words you hear from (the guy that plays the President on 24, Denis Heybert or something) is “Kill them, kill them all”. And then the damn credits roll!!! Just when we thought his character was starting to get sympathetic!
I was more disappointed when it was cancelled than any other show I’ve seen.