The Orange County Register has an amusing pictorial about who the Ducks biggest/most hated rivals are.
http://www.ocregister.com/articles/ducks-246718-rivals-top.html?pic=1
Personally, I think the Devils is a complete nobrainer considering it was Rob who was instrumental in luring his brother from the Dark Side. Rob’s betrayal is tantamount to Johnny Damon defecting to the New York Nazis.