Kotelnik is a weak champion but far, far from the worst of all time and probably only got name dropped cause Khan wants his title, but that is REALLY bad promotion. Do you really want your fan base knowing that you are targeting a guy because he is one of the weakest world champions around and would be the easiest route to a title? Doesn't say a lot if you beat the "worst champion of all time" to become a champion yourself if that's how it's promoted.
Anyway, back to the point. Who do people here think is the worst? In recent times it would probably be Carlos Maussa, but I'd have to do further research to determine the ultimate worst.