Who was the most influential character?

In The Merchant of Venice there were many characters that played huge roles or had very important lines in the play. But, who was the most influential character in the play. By influential I mean the character that had the biggest effect on the other characters lives. There are a couple clear choices, like Portia, Antonio or Shylock. These three characters all had moments where they were very compassionate and influenced the play very heavily. For Portia it was her mercy or justice speech when she disguised herself as a lawyer in Antonio and Shylock's trial. For Shylock it was his speech asking why he was treated differently because he was Jewish. And for Antonio it was his letter to Bassanio asking for him to come visit him before he goes to trial with Shylock. Given these three examples, the most influential moment that these characters had was Portia when she gave her mercy or justice speech.