big man vs top dog

big man

noun
  • A corrupt, autocratic ruler. 

  • Synonym of big guy (“term of endearment”) 

  • A male individual in a tribe who has great status and influence, especially in Melanesia and Polynesia. 

top dog

noun
  • The boss, the leader (of the pack). 

  • In a competition, the one expected to win. 

How often have the words big man and top dog occurred in a corpus of books? (source: Google Ngram Viewer )