In Sicily - Toto Riina, no doubt.
Toto' Riina may have been great at conducting mafia wars, but in my opinion he sucked at maintaining contacts with politicians. He just wanted them to be his pet dogs. If they disobeyed, he killed them (see Salvo Lima).
+1 on that,there were much smarter bosses in Sicily than Toto Riina,he wanted to kill everybody who went against him,or disobeyed.That's not way mafia should operate,after Toto Riina's violence state went in battle against them which led to a lot of bosses being arrested etc.
For Sicily i would say Calogero Vizzini.
