It depends what you enjoy. Some enjoy turm pure/rune pure pking because hits are more frequent and bridding usually consists of a lot less OP gear. Main pking relies a lot more on prod specs & huge hits in order to get a kill.
It depends what style of pking you're going for, cause personally I'd prefer a turm rune pure or turm zerk to a barrows pure because in my opinion pking on lower leveld accounts is a lot more fun. Then again things like mid level/main bridding has its perks.