This is easy.
Dave Schultz changed the game completely and in the process drew the ire of fans, coaches, players, and league officials from coast to coast in 2 countries.
No one had the effect he had. There have been "hated" players like Linesman, Avery, Cooke, Crosby,
Dale Hunter,
Claude Lemieux, and others like that but none were game changers like Schultz was, he totally changed the way the game was played using intimidation like no one before him and really, no one since. There have been tough teams, sure, but none like those 2 Stanley Cup winning Flyer teams with Schultz leading the way and man, he was hated like no one else.
For me,
Claude Lemieux was my most hated player followed closely by
Dale Hunter. Those 2 guys could just drive you nuts with their style of play as they would cheat their way to wins and when someone tried to make them pay they always seemed to skate away unscathed, for the most part and often wouldn't even get a penalty but the other team would, it was just maddening to watch that!
I still think Lemieux should have been suspended forever for the Draper hit, it was so obviously on purpose and the fact he never apologized for it really says what kind of a low life he is and was.