Wow, I didn't have any idea that Sideshow Bob Roberts was so... unloved? Maybe it's one of the weakest use of the character out of the list, but as an episode is in the top, unlike Black Widower, that in my opinion has the weakest use of the character (Sideshow Bob is a criminal but money is not something should incentive him to kill) and also the weakest story (such a series of casualties, like in Funeral for a Fiend).
Krusty Gets Busted [17]
Black Widower [12] -2
Cape Feare [17]
Sideshow Bob Roberts [7] +1
Gone Boy [10]