If your main objective is to kill off as many major NPCs you're better off siding with Djikstra. That way you get to play a direct hand in the death of Radovid, Roche, Ves, Thaler and later on Emhyr.- Radovid has to be king of the north (Reason of State ignored). I contemplated killing Radovid but then realized lore-wise more people would probably die if he stayed in power. Plus then Emhyr dies for not winning the war.
Also if you ignore Cave of Dreams, I believe Blueboy Lugos dies? Then you can side with Cerys/Hjalmar and kill Madman Lugos personally. Or just ignore all major quest relating to Crach's children so Hjalmar's buddies die.
While you're at it, I'd kill all friendly monsters (Salma, Bart etc) and all those Scoia'tael thieves


