If I read the title, it says in franchise history. This means that during the time of their tenure in Buffalo, they were polarizing or afterwards there is reasonable debate about them.
For me in no particular order,
Kelly- Great QB, who didn't want to be here, drank like a fish, and beat women.
OJ- during career had one eye always on Hollywood, post career had one hand one on the knife.
Ralph- because he was cheap.
RJ/Flutie- the debate lingered for a long time, one QB aged, the other just sucked
Tyrod- guy leads team to playoffs first time in almost 20 years, and is still traded to Cleveland.