Is emotion the most likely influence of a person's behavior?

I believe that your question is asking to make a comparison between emotion and logic.  If that is the case, then yes, I believe that emotion is most likely to influence a human decision more than logic and reasoning.  Advertising companies believe it too.  That is why so many advertisements try to get you emotionally involved.  Truck commercials tug on the patriotic emotional heart strings.  Breakfast cereal commercials make it seem like you'll be a...

I believe that your question is asking to make a comparison between emotion and logic.  If that is the case, then yes, I believe that emotion is most likely to influence a human decision more than logic and reasoning.  Advertising companies believe it too.  That is why so many advertisements try to get you emotionally involved.  Truck commercials tug on the patriotic emotional heart strings.  Breakfast cereal commercials make it seem like you'll be a better parent if you buy a certain product.  Jeep commercials sell you the feeling of power, control, and masculinity.  The list can go on and on.  Nigel Holis works in the advertising business and wrote the following:

Instead, it [advertisement] creates positive memories and feelings that influence our behavior over time to encourage us to buy something at a later date. 

I linked the rest of the article below.  Notice that he doesn't claim advertisements try to activate logical brain centers.  He says that the ads target feelings that influence our behaviors.  

I absolutely agree that emotion influences teenagers more than logic.  Until recently, I could only give anecdotal evidence to support those feelings.  But many brain studies have come out that show that the logic based centers of the brain are not fully developed until the age of 25, while the emotional based centers of the brain are fully operational by the teenage years.  This means that when I ask a teenager "what were you thinking?" when he/she does something dumb, that teenager can legitimately say "I wasn't thinking, I was feeling."  I linked a summary from the National Institutes of Health below.  

Yes, emotion is a very powerful influence on people.