Thousand Sons and Space Wolves (though Thousand Sons didn't really care until after the Propero incident, there used to be rules for this in old Space wolves codex)
Thousand Sons and Death Guard
Salamanders/Iron Hands/Raven Guard and Word Bearers/Night Lords/Iron Warriors/Alpha Legion (for stabbing them in the back at Istvaan, used to be some rules for this in IA)
Iron hands and Emperor's Children (after initial betrayal before Istvaan)
... In fact a lot of legions were sick to death of the Emperor's Childrens arrogance...
Night Lords and Dark Angels? (I've only read savage weapons when it comes to these two...)
Thousand Sons and World Eaters
World Eaters and Emperors Children
There must be someone the World Eaters particularly hated before the heresy, considering all their anger. I know they always didn't really trust the Thousand Sons but had respect for the iron warriors. I guess they had enough hate to go around for everyone..